Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://www.arcetri.astro.it/science/chianti/chianti_5.1/cug.pdf.gz Äàòà èçìåíåíèÿ: Thu Sep 15 17:22:50 2005 Äàòà èíäåêñèðîâàíèÿ: Sat Dec 22 08:14:16 2007 Êîäèðîâêà: Ïîèñêîâûå ñëîâà: guide 8.0

CHIANTI
An Atomic Database for Sp ectroscopic Diagnostics of Astrophysical Plasmas
USER GUIDE ­ Version 5.0 ­ 4 August 2005 Written by Giulio Del Zanna with contributions from Peter Young and the team memb ers.

Contents
1 What's new in Version 5.0 2 What was new in Version 4.1 3 What was new in Version 4.0 4 Intro duction 4.1 What is CHIANTI . . . . . . . . . . . . . . . . 4.2 Imp ortant caveats and limitations . . . . . . . . 4.3 How to acknowledge CHIANTI . . . . . . . . . 4.4 The CHIANTI consortium memb ers . . . . . . . 4.5 A short history of the package . . . . . . . . . . 4.6 How to keep up dated on CHIANTI developments 5 The database structure 5.1 Directory structure and atomic data 5.1.1 Ionization/recombination . . 5.1.2 Final comments . . . . . . . 5.2 Additional ancillary data . . . . . . file .. .. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4 4 6 6 6 7 8 8 9 10 10 13 13 13 15 16 16 19 20 21 21 24 24 27 28 28 29

contents . . ........ ........ ........

6 The Software structure 6.1 Short description of the CHIANTI software . . . . . . . . . . . . . . . . . . . 6.2 How to find help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 The CHIANTI distribution and installation 7.1 Installing CHIANTI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.1 Installing CHIANTI within SolarSoft . . . . . . . . . . . . . . . . . . 7.1.2 Installing CHIANTI indep endently as a stand-alone . . . . . . . . . . 8 Theory and definitions 8.1 Optically thin emission lines . . . . . . . 8.1.1 The stellar case . . . . . . . . . . 8.2 Proton rates . . . . . . . . . . . . . . . . 8.3 Non-Maxwellian particle distributions . . 8.4 Photo excitation and Stimulated Emission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


8.5 8.6 8.7

8.4.1 Implementation of Photo excitation and Photo excitation by arbitrary radiation fields . Ionization and recombination . . . . . . . . . Continuum calculations . . . . . . . . . . . . . 8.7.1 Two photon continuum . . . . . . . . . 8.7.2 Bremsstrahlung . . . . . . . . . . . . . 8.7.3 Free-b ound continuum . . . . . . . . .

Stimulated ...... ...... ...... ...... ...... ......

Emission ...... ...... ...... ...... ...... ......

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30 30 31 32 32 33 33 34 34 36 36 38 38 41 41 41 43 44 45 47 48 49 49 50 51 51 51 52 52 54 54 54 55 56 59 60 63 67 67 70

9 Some examples on how to use the software 9.1 Calculating line intensities. . . . . . . . . . . . . . . . . . . . . . . . . 9.2 Saving, restoring and exp orting the CHIANTI line intensities structure 9.3 Create a latex or ascii file with all the line details . . . . . . . . . . . . 9.4 Calculating continuum intensities . . . . . . . . . . . . . . . . . . . . . 9.5 Creating a synthetic sp ectrum with the continuum . . . . . . . . . . . . 9.5.1 Create a sp ectrum in the isothermal approximation . . . . . . . 9.6 The user-friendly multi-purp ose widget ch ss.pro . . . . . . . . . . . . . 9.6.1 SECTION 1 - The Calculation of the CHIANTI line intensities. 9.6.2 SECTION 2 - calculation of a synthetic sp ectrum . . . . . . . . 9.6.3 SECTION 3 - selection of parameters for plotting and output . 9.7 Photo excitation from any user-provided radiation field . . . . . . . . . 9.8 Non-maxwellian distribution of electron velo cities . . . . . . . . . . . . 9.9 Lo oking at level p opulations . . . . . . . . . . . . . . . . . . . . . . . . 9.10 Lo oking at the pro cesses that p opulate each level . . . . . . . . . . . . 9.11 Searching for a line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.12 Lo oking at the different ionisation equilibria . . . . . . . . . . . . . . . 9.13 Density and temp erature diagnostics from line ratios . . . . . . . . . . 9.13.1 The DENS PLOTTER and TEMP PLOTTER widgets . . . . . 9.13.2 The DENSITY RATIOS pro cedure . . . . . . . . . . . . . . . . 9.13.3 The TEMPERATURE RATIOS pro cedure . . . . . . . . . . . . 9.13.4 The CHIANTI NE and CHIANTI TE widgets . . . . . . . . . . 9.13.5 The PLOT CHIANTI NE and PLOT CHIANTI TE pro cedures 9.13.6 Calculating temp eratures by using different ions . . . . . . . . . 9.14 Calculating contribution functions . . . . . . . . . . . . . . . . . . . . . 9.15 Calculating radiative losses . . . . . . . . . . . . . . . . . . . . . . . . . 9.16 The calculation of the DEM . . . . . . . . . . . . . . . . . . . . . . . . 9.16.1 Controlling the pro cedure . . . . . . . . . . . . . . . . . . . . . 9.16.2 Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.16.3 Some final remarks . . . . . . . . . . . . . . . . . . . . . . . . .

A Description of the CHIANTI V.4 software up dates A.1 Routines already available in Version 3 . . . . . . . . . . . . . . . . . . . . . A.2 Other routines that were previously available only within SolarSoft . . . . .

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B Incorp orating proton rates into CHIANTI B.1 The proton rate data files . . . . . . . . . . . . . . . . . . . B.2 Reading the .psplups file . . . . . . . . . . . . . . . . . . . . B.3 Changes to p op solver.pro . . . . . . . . . . . . . . . . . . . B.4 Implementing proton rates in user-written routines . . . . . B.5 The proton-to-electron ratio . . . . . . . . . . . . . . . . . . B.5.1 Implementing proton rates in user-defined pro cedures C Incorp orating 9 p oint spline fits into user-defined C.1 Data file format changes . . . . . . . . . . . . . . . C.2 Changes to existing software . . . . . . . . . . . . . C.2.1 Routines that call read splups . . . . . . . . C.2.2 read splups . . . . . . . . . . . . . . . . . . C.2.3 descale all.pro . . . . . . . . . . . . . . . . . C.2.4 p op solver.pro . . . . . . . . . . . . . . . . . D The extra set of complementary routines D.1 Definitions . . . . . . . . . . . . . . . . . . . D.2 The primary routines . . . . . . . . . . . . . D.2.1 p op plot.pro . . . . . . . . . . . . . . D.2.2 integral calc.pro . . . . . . . . . . . . D.2.3 temp plotter.pro and dens plotter.pro D.2.4 show p ops.pro . . . . . . . . . . . . . D.2.5 g of t.pro . . . . . . . . . . . . . . . D.3 The secondary routines . . . . . . . . . . . . D.3.1 emiss calc.pro . . . . . . . . . . . . . D.3.2 emiss select.pro . . . . . . . . . . . . D.3.3 ion interp.pro . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pro .. .. .. .. .. .. . . . . . . . . . . . . . . . . . . . . . .

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71 71 72 72 72 73 73 74 74 74 75 75 76 76 76 77 79 79 79 80 80 80 81 81 81 81 82 82 85

cedures ..... ..... ..... ..... ..... ..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

E More details E.1 The CHIANTI line intensities structure . . . . . . . . . . . . . . . . . . . . . E.2 The CHIANTI sp ectrum structure . . . . . . . . . . . . . . . . . . . . . . . .

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1

What's new in Version 5.0
· Inclusion of ionization and recombination effects in level p opulation calculation Sect. 8.6, Sect. 5.1.1. · Photo excitation from any user-provided radiation field · Non-maxwellian distribution of electron velo cities · New data for ­ Fe IX, Fe X, Fe XI I, Fe XV (EUV) ­ Fe XVI I to Fe XXIV (X-rays) ­ n=3 to n=3 transitions for N-like and O-like ions ­ new ions (P XIV, XV; Cl I I, X, XI, XI I, XVI I; K V, XVI I, XIX; Ca VI I, VI I I; Co XX; Zn XXI I I) · The software has b een improved and sp eeded. Fixed various minor bugs. · A few new useful routines, in particular: which_line pop_processes (see the example section). · Added keV option to calculate/plot sp ectra in energy units. ­ see

­ see Sect. 8.5 and Sect. 9.7

­ see Sect. 8.3 and Sect. 9.8

The changes intro duced to sp eed the calculations were made necessary by the increasingly larger atomic mo dels now available in CHIANTI, that made the running time of the software of the previous version to o long. The software is backward-compatible, i.e. can b e used together with previous versions of the database.

2

What was new in Version 4.1

-Added detailed descriptions of the data file contents. -Replaced the continuum plot, that was created with the corrupted version of the itoh.dat file. -Corrected instructions for installation within Windows.

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3

What was new in Version 4.0

This do cument describ es the general characteristics of the new Version 4.0 of the CHIANTI package (database and IDL pro cedures). A considerable numb er of new features, b oth in the database and the software, have b een added (see Young et al., 2003). We have tried to keep a distinction b etween the previous and the new features in this do cument. Users of previous versions, please NOTICE: 1. The pro cedures to install CHIANTI as a stand-alone package have changed in small but imp ortant ways. 2. New kinds of files (.fblvl and .psplups) are now b eing distributed and the format of the .splups files has changed. 3. The entire previous software has b een rewritten. There are a few minor changes in the way the pro cedures are called. 4. New software has b een written. 5. The CHIANTI routines now use SolarSoft routines. The main new features describ ed in this guide are · New CHIANTI distribution and structure · Photo excitation and Stimulated Emission · New software ­ see Sect. 6.1 and App. A ­ see Sect. 8.7 ­ see App. B ­ see App. C ­ see Sect. 7 ­ see Sect. 8.4

· New continuum calculations

· Incorp orating proton rates into CHIANTI

· Incorp orating 9 p oint spline fits into CHIANTI

Backward compatibility has b een assured for almost all cases. In practice, previous users of CHIANTI will b e able to use the new V.4 software as b efore, with just minor changes. On the other hand, software versions prior to 4 are not compatible with the v.4 database. This do cument replaces the previous CHIANTI guide (Version 1.0).

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4

Introduction

CHIANTI is a collab orative pro ject involving researchers based at the Naval Research Laboratory (NRL, Washington DC, USA), Rutherford Appleton Lab oratory (RAL, UK), the University College London (UCL, UK), the University of Cambridge (UK), the George Mason Univerity (GMU, USA) and the University of Florence (Italy).

4.1

What is CHIANTI

The CHIANTI package consists of a critically evaluated set of atomic data (energy levels, wavelengths, radiative transition probabilities and excitation data) for a large numb er of ions of astrophysical interest. It also includes a numb er of ancillary data and a suite of Interactive Data Language (IDL) programs to calculate optically thin synthetic sp ectra and to p erform sp ectral analysis and plasma diagnostics. Plasma emission co des have long b een used to study UV and X-ray sp ectral lines emitted from solar or stellar atmospheres. A comparison of the theoretical line intensities with the observed intensities allows a determination of the physical parameters for the plasma (cf Mason and Monsignori Fossi, 1994 and Del Zanna, Landini and Mason, 2002). It is very imp ortant, now that high accuracy atomic data are available, to improve and keep up-to-date the plasma co des. The CHIANTI database has b een used extensively by the astrophysical and solar communities to analyse emission line sp ectra from astrophysical sources. The CHIANTI package is freely available at one of the CHIANTI homepages: · RAL, UK: http://www.chianti.rl.ac.uk/ · NRL, USA: http://wwwsolar.nrl.navy.mil/chianti.html · UCL, UK: http://www.mssl.ucl.ac.uk/www solar/chianti/ · DAMTP, UK: http://www.damtp.cam.ac.uk/user/astro/chianti/chianti.html · GMU, USA: http: · Univ. of Florence, Italy: http://www.arcetri.astro.it/science/chianti/chianti.html or at · SolarSoft, a programming and data analysis environment for the solar physics community. http://www.lmsal.com/solarsoft/

4.2

Imp ortant caveats and limitations

As with any atomic data package, CHIANTI has b een develop ed to suite some sp ecific applications in astrophysics, and users should read the CHIANTI pap ers and the do cumentation to find out the ranges of applicability of the package. Currently, some of the main assumptions and limitations of the data and programs are: 6


· The plasma is collisionally excited by electrons, protons and photons. · Electrons and protons have Maxwellian distribution functions. Indeed CHIANTI data include Maxwellian-averaged electron and proton collision strengths. However, it is p ossible to study the effects of particle distributions that are linear combinations of Maxwellians of different temp eratures. · Electrons and protons have the same temp erature. · The plasma ionization is dominated by collisions (i.e. no photo-ionization is included). · Atomic pro cesses affecting the ionisation state of an element can b e separated from those affecting the level balance within an ion. A correction to the level p opulations due to ionization and recombination is included, but it is only valid up to densities ab ove which metastable level p opulations b egin to b e non-negligible. · The plasma is in a steady state. · All lines are optically thin. · Line emissivities are reliable only in some (extended) temp erature and density ranges. The ranges of temp eratures at which the original rates were calculated are normally listed in the files. · The current ion fractions that are provided within CHIANTI have b een calculated assuming equilibrium and without taking into account density effects. · If differential emission measures are used, large deviations in line intensities (compared to observed values) can b e found.

4.3

How to acknowledge CHIANTI

The continued development of the CHIANTI database is dep endent on continued funding which is generally available if we can demonstrate that the CHIANTI database is of use to astrophysical research. If you use CHIANTI, we only ask that you acknowledge it appropriately in any publications: Write in the text of any publication the reference to the CHIANTI pap er asso ciated with the particular VERSION you have used: · 1.x - (Dere et al., 1997; AASS, 125, 149) · 2.x - (Landi et al. 1999; AASS, 135, 339) · 3.x - (Dere et al., 2001; ApJSS, 134, 331 ) · 4.x - (Young et al., 2002 ). · 5.0 - (Landi et al., 2005 ) 7


We would appreciate if you also write in the acknowledgements of any publication the following: CHIANTI is a collab orative pro ject involving NRL (USA), RAL (UK), and the following Universities: College London (UK), of Cambridge (UK), George Mason (USA), and of Florence (Italy). If a detail work on a particular ion is done, it would b e appropriate to also refer to the original publication. References can b e found at the end of each data file or on the WWW. CHIANTI data are included into other databases. It would b e appropriate to make that clear to the users so they can trace back the results they use to the original calculations. Users should b e aware of what is included in the database, of the approximations applied, and of the atomic data used. The CHIANTI results should not b e blindly considered valid in all cases. For example, the CHIANTI predicted emissivities should not b e used when considering temp eratures outside of the validity ranges. Any contributions and suggestions to CHIANTI are welcomed. We would appreciate a short description of how you employ CHIANTI.

4.4

The CHIANTI consortium memb ers

The CHIANTI pro ject was originally set up by Dr. Ken Dere of the Naval Research Lab oratory (Washington, USA), Dr. Helen Mason of the Department of Applied Mathematics and Theoretical Physics at the University of Cambridge (UK), and Dr. Brunella MonsignoriFossi of the Arcetri Astrophysical Observatory (Florence, Italy). Former students of Dr. Monsignori-Fossi (Dr. Enrico Landi) and Dr. Mason (Dr. Peter Young) help ed in the creation of the database. The sad and unexp ected death of Dr. Monsignori-Fossi in January 1995, led to Prof. Massimo Landini, a close asso ciate of Dr. Monsignori-Fossi, b ecoming a new CHIANTI representative (University of Florence). Additional collab orations have involved Dr. Dave Pike of the Rutherford Appleton Lab oratory (RAL), who has written CHIANTI routines to run within the environment of the SOHO/CDS software (and within SolarSoft), and with Dr. Gordon Bromage, Dr. Barbara Bromage and her former student Dr. Giulio Del Zanna of the University of Central Lancashire. Dr. Enrico Landi, now at the Naval Research Lab oratory, Dr. Peter Young, now at RAL, and Dr. Giulio Del Zanna, now at UCL, have continued to b e active collab orators in the CHIANTI pro ject.

4.5

A short history of the package

1. The first version of the CHIANTI database was released in 1996 and is describ ed in Dere et al. (1997). Young et al. (1998) used the CHIANTI database for a detailed comparison with observed EUV solar sp ectra to assess the diagnostic accuracy of the two data sets. 2. Version 2.0 (Landi et al. 1999) was released in April 1999. This Version adds atomic data for many of the so called minor ions (Na, P, Cl, K, Ti, Cr, Mn, Co, and Zn), not 8


included in the first version. Because the astrophysical abundances of these elements are relatively low, only the strongest lines of these elements are observed. The addition of the minor ions is an imp ortant step in our goal to understand astrophsical sp ectra in detail. In addition, Version 2.0 extends the b eryllium-like sequence, up dates some of the data in Version 1, and provides an IDL pro cedure to calculate the continuum. 3. Version 3.0 of the CHIANTI database was released in Septemb er 2000 (Dere et al., 2001). In this version the database has b een extended to wavelengths shorter than 50° by including atomic data for the hydrogen and helium iso electronic sequences, A inner-shell transitions and satellite lines and several other ions. In addition, some of the ions already present in the database have b een up dated and extended with new atomic data from published calculations. The inclusion of the satellites has required a significant mo dification to the manner in which the sp ectra have b een calculated with CHIANTI. Consequently, a new version of the IDL software has b een pro duced. In Novemb er 2000 we have released a whole new CHIANTI package under SolarSoft. 4. Version 4 of the CHIANTI database, released in Sept. 2002 (Young et al., 2002). The ma jor changes are the inclusion of proton excitation data, principally for ground configuration levels which are close in energy, and of photo excitation. The fitting pro cedure for excitation data, b oth electrons and protons, has b een extended to allow 9 p oint spline fits in addition to the previous 5 p oint spline fits. This allows higher quality fits to data from close-coupling calculations where resonances can lead to significant structure in the thermally-averaged collision strengths. With the addition of H I, He I and N I, the first neutral sp ecies have b een added to CHIANTI. Many existing ion data-sets have b een up dated, in particular most ions of the nitrogen and b eryllium iso electronic sequences. Also, new ions have b een added, including Ar IV, Fe VI and Ni XXI. The continuum routines have b een re-written, including a new relativistic free-free continuum, a new free-b ound, and a new two-photon continuum. New software has b een written. Minor releases of the database and the software normally include fixes and might o ccur a few times p er year.

4.6

How to keep up dated on CHIANTI developments

· Read the CHIANTI NEWS page on the WWW. · Read the HISTORY (software) and README (database) files in the distribution. Any news and changes are logged in these files. The first one has the details of all the software changes, while the second one describ es the changes to the database. These files can b e found directly in the distribution or via links on the WWW pages.

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· We maintain an e-mail list, that is used to distribute information ab out any developments of the CHIANTI database and programs. To get on the CHIANTI e-mailing list, send us an email. · We also have an e-mail adress for questions: chianti_help@halcyon.nrl.navy.mil

5

The database structure

The atomic data will continue to b e up dated regularly as new data are calculated or measured in the lab oratory. It is intended that these atomic data can b e accessed and transfered into users own analysis programs, for more sophisticated applications.

5.1

Directory structure and atomic data file contents

The database has a tree structure, with the top directory designated with the IDL system variable !xuvtop (and named dbase within SolarSoft): dbase/ In the top directory are the following files: README_CHIANTI VERSION Then, there Each element The filename For example, he/ he_1/ he_2/ Then, we have a series of ancillary data that are contained in various subdirectories: masterlist/ has the list of the ions currently present in the database with elemental abundance files. contains files for the continuum calculations. has DEM files. 10 with the description of the current version. with the version number.

is a series of subdirectories, one for each element present in the databas has a subdirectory for each ion. prefix for each ion follows spectroscopic notation. for He, we have He I and He II subdirectories:

abundance/ continuum/ dem/


ioneq/ contains ionization fraction files. ip/ has ionization potentials. ancillary_data/instrument_responses/ with effective areas. There are five primary ASCI I files for each ion sub directory. For example, for Fe XIV we have: · fe_14.elvlc Sp ecifies the energy levels in cm-1 and Rydb ergs. It includes b oth exp erimental data and theoretical values of the levels energies. The energy levels are obtained from NIST. Where necessary, these are supplemented by other lab oratory and theoretical values. Each column in the files has: 1. Index of the fine structure energy levels. This index applies to all files for this ion. 2. Configuration numb er, a progressive numb er. This value is not used by the software. 3. Designation of the fine structure level,usually using the notation of LS coupling. 4. Integer value of 2S+1, S=spin in standard usage 5. Integer value of angular momentum L. 6. Symb ol for L, i.e. S for L=0, P for L=1, D for L=2, etc. 7. Total angular momentum J 8. Multiplicity or statistical weight: 2J+1 This value is not used by the software. 9. observed energy in cm-1 (if there is no observed value, it is set to zero). This value is used by the software. 10. Observed energy in rydb ergs This value is not used by the software. 11. theoretical energy in cm-1 (usually this is the energy from the scattering calculation, but not necessarily). This value is used by the software. 12. Theoretical energy in rdyb ergs. This value is not used by the software. 13. There might b e further columns but these are not read by the software. Note that the ordering of the levels do es not follow any strict rule. · fe_14.wgfa Contains the wavelengths, gf and A values of the transitions and the indices initial and final level corresp onding to the indices of the levels as given in the fe_14.elvlc file. Wavelengths calculated from the theoretical energies are of an indeterminate accuracy and their values are presented as negative values of the calculated wavelength. The `observed' wavelengths in these files are based on the exp erimental energies and should b e the b est available. 11


The radiative data are taken from published literature and where necessary, supplemented by new calculations. Each column in the files has: 1. index of the lower energy level (consistent with the ordering in the .elvlc file) 2. index of the upp er energy level 3. wavelength in Angstroms. If the wavelength do es not connect 2 observed energy levels, the wavelength is given as a negative numb er. Two-photon transitions are given a zero wavelength. 4. gf value (weighted oscillator strength) 5. A-value 6. In some cases additional columns have extra information on the transition. These are not read by the software. · fe_14.splups contains the p oint spline fits to electron collision strengths scaled according to the the rules formulated by Burgess and Tully (1992), as describ ed in Dere et al. (1997). All the atomic data in the CHIANTI database have b een visually displayed and assessed for accuracy and any sp oradic errors which sometimes creep into published results. Accurate replication of the temp erature averaged collision strength over a wide range of temp eratures can b e accomplished with the data in this file. Each column in the files has: 1. Z (6 = C) 2. ion (3 = I I I) 3. index of the lower level (consistent with the ordering in the .elvlc file) 4. index of the upp er level 5. transition typ e: see Burgess and Tully, 1992, A&A. typ es 1-4 follow Burgess and Tully for a 5 p oint spline fit typ e 5 = dielectronic recombination excitation rate typ es 6-9 are the same as 1-4 but for 9 p oint spline fits 6. g f -value 7. Energy difference b etween the two levels in Rydb ergs 8. Value of scaling parameter 'C' (cf. Burgess and Tully, 1992, A&A). 9. 5- or 9-p oint values (spline fits) of the scaled Upsilons. · fe_14.psplups This is analogous to the fe_14.splups file, and contains the p oint spline fits to proton collision strengths. · fe_14.fblvl contains data used for the free-b ound calculation. Namely, the statistical weights for each nl shell, and the energy levels in cm-1 . 12


5.1.1

Ionization/recombination

We created two new files that include the ion and rec rates. The names of these files follow the usual CHIANTI pattern, and have the .CILVL and .RECLVL suffixes, for ionization and recombination resp ectively. Data in these files are tabulated as a function of temp erature, at all temp eratures for which they are provided. Currently, all the rates for each ion are given at the same temp erature. In the future this will b e generalised. 5.1.2 Final comments

The basic structure of the files is to put the data at the b eginning of the file followed by comments. The comments must b e enclosed at the end of the file b etween two lines containing a single '-1' The original sources are do cumented in each data file, where also additional and detailed comments written by the CHIANTI memb er that assessed that particular ion can b e found. You can have direct access to the references via the WWW pages.

5.2

Additional ancillary data

Some additional data files are needed in various calculations. The software allows the selection of these files, from either a 'standard' selection provided within the database, or by using user defined files that are included in the current working directory, provided they have the prop er file extension. For example, it is p ossible to create a user defined 'myfile.dem'. If the file is in the working directory, then the file will automatically b e app ended to the list of available DEMs from the CHIANTI database. In other cases, it is p ossible to select the file by using a widget that allows the user to change directory. Any user-defined file must have the same format as those already provided (also including a 'comment' section at the end of the file) The list of the ions present in the database A !xuvtop/masterlist/masterlist.ions file keeps the current database. This list is used as default by many routines (for example intensities). In some cases, it is p ossible to instead use a user-defined list of ions, or to directly supply the routines with a list of ions, via the SNGL Elemental abundances Files with various elemental abundances are provided in the directory !xuvtop/abund/ Element abundances are in the usual dex notation (Log10 values, relative to H, that has a Log10 value of 12). list of all the ions in the those that calculate line to sp eed the calculation, ION keyword.

13


Options are available within the routines to cho ose different elemental abundances. Userdefined abundance files can also b e used, and should have a .abund file extension. Be aware that any element missing in the elemental abundance file will also b e missing in any output created by any software that reads the elemental abundance file. There is a great deal of controversy over the variation of the elemental abundances in the solar and stellar atmospheres. See the reviews of Meyer (1985, 1993), Widing and Feldman (1992), Mason (1992), Raymond et al. (2001). Also, it should b e kept in mind that different analyses can lead to very different results. For example, the ionisation balance, the selection of lines, and the sp ectroscopic metho d used can each account for a variation of a factor of two or more in the derived element abundances (see Del Zanna et al., 2002 and references therein). Ionisation Fractions Files giving collisional ionization equilibria are provided in the !xuvtop/ioneq directory. User defined ionisation files should have a .ioneq file extension. Be aware that most CHIANTI software uses the temp eratures in these files as a base for the calculations. For example, if DEM(T) values are supplied, they are first interp olated at the temp eratures in the ionization fraction, and the calculations are done at those temp eratures. The ionisation fractions have b een taken from the tabulated values in the published literature (e.g. Arnaud & Raymond, 1992; Arnaud & Rothenflug, 1985; Mazzotta et al., 1998). Be aware that any ion missing in a ionisation fraction file will also b e missing in any output created by the software. Also, b e aware that any line missing a temp erature overlap with the chosen ionisation fraction would have zero emissivity and will not b e output by the software. Be aware that large differences b etween different tabulations are present, and that large uncertainties are asso ciated with these calculations. It should b e noted that the ionisation equilibrium plays a ma jor role not only in the derivation of the D E M , but also in that one of the elemental abundances. In this resp ect, it is imp ortant to b e aware of the fact that a numb er of ions, in particular those of the Li and Na iso electronic sequence, present anomalous b ehaviour (see Del Zanna et al., 2002, and references therein). Differential Emission Measure Files sp ecifying various standard differential emission measures (D E M ) distributions for different solar features are provided in the !xuvtop/dem directory. Additional files for stellar atmospheres will also so on b e added. Each file contains the Log10 T and Log10 DEM values in two columns, ordered with increasing temp erature. User-defined DEM files should have a .dem file extension and must have the same format and ordering of the files provided. Be aware that any line missing a temp erature overlap b etween the ion fraction and the chosen D E M distribution would have zero emissivity and will not b e 14


output by the software. The emission measure distribution in the solar atmosphere is a complex issue. Starting with the pioneering work by Pottasch (1964), sp ectra in the UV wavelength range have b een used to determine the distribution of material as a function of temp erature, following various metho ds. More details can b e found in Section 9.16. Other files Other files are in other miscellaneous directories. For example: !xuvtop+'/ip/chianti.ip' has the ionization p otentials for all the ions; !xuvtop+'/continuum/ contains data used by the routines that calculate the continuum. For example, gffgu.dat contains the free-free gaunt factors of Sutherland (1998).

6

The Software structure

A numb er of Interactive Data Language (IDL) pro cedures are also provided as part of the CHIANTI package. These include routines to read the various CHIANTI database files, calculate level p opulations, line intensities, and temp erature dep endent and density dep endent line intensity ratios. Most of our efforts have gone into developing well-do cumented user-friendly IDL routines that meet readily apparent needs. We welcome contributions to the software. CHIANTI has b een run mainly on Sun, Dec Unix workstations and on PCs with Linux. CHIANTI also runs (with some small limitations) under Windows NT and in VMS. Please rep ort to us any problems you might find. All the IDL routines have b een do cumented with extensive headers giving detailed descriptions and examples. Please read them carefully. The CHIANTI routines can b e group ed into three classes: · Low-level routines, that for example read the files in the database, or p erform the level p opulation calculations. These are not describ ed here and should not b e used directly byt the users. · High-level routines, that p erform more complex op erations and can b e called from the command line. These routines usually output arrays or structures, and optionally pro duce plots, p ostscript output or ascii files. Most of them have a long list of options, commanded via KEYWORDS. Please read the headers. · Higher-level widget-typ e routines. These routines are more user-friendly, and are complementary of the ab ove class. These routines call low-level or high-level routines to p erform the calculations. The CHIANTI routines are organised in a tree structure. The main level contains some high-level pro cedures and the HISTORY file, where all mo difications to the software are logged. 15


6.1

Short description of the CHIANTI software

Now, a description of the various high-level routines that are present within the CHIANTI software tree is given. Compared to previous releases, significant changes o ccurred. Please read Sect. ?? for details. A new set of high-level and higher-level routines has b een written for Version 4. The ma jor change for V.4, aside from those already mentioned, has b een the way to calculate synthetic sp ectra and handle line intensities (see Fig. 1): · A new routine, ch_synthetic.pro, calculates (without any abundance factor) line intensities or G(T ), and outputs a line intensities CHIANTI structure (see Sect.E.1 for details). This IDL structure can b e saved and later restored in various ways, for example using ch_write_fits and ch_read_fits. · ch_line_list.pro takes the line intensities CHIANTI structure and creates ascii or latex files with lists of line identifications and intensities. · make_chianti_spec.pro This program creates the CHIANTI SPECTRUM structure (read Sect. E.2 for details), that contains the synthetic sp ectrum, created by multiplying by the abundance factor the line intensities and adding the continuum (optional). · Finally, a new multi-purp ose widget ch_ss.pro has b een written. It includes all the ab ove features. Other routines that previously were only available within SolarSoft are also included now. The users therefore now have various different routines to cho ose from. We have kept the older high-level routines, so the user can still use them as b efore (with slight mo difications/additions of keywords). We have up dated them and re-written as wrapp er routines (essentially that call the newly-written routines) as follows:

6.2

How to find help

For the first two classes of routines, by simply typing the name of the routine, a description of how to call the routines, with examples, is printed. For example, IDL IDL IDL IDL IDL IDL IDL > > > > > > > temperature_ratios temperature_ratios,ion,wmin,wmax,Log10(tempmin),Log10(tempmax),$ temperature,ratio,description,$ [pressure= ,density= , psfile= , outfile= ] i.e.: temperature_ratios,'c_5',40.,50.,5.,7.,temp,rat,desc

In any case the b est way to understand what a routine do es and how it works is to read the header do cumentation with e.g.: 16


ch_ss synthetic synthetic_plot isothermal make_chianti_spec ascii_wvl_dem latex_wvl_dem ch_synthetic ch_line_list

emiss_calc gofnt g_of_t dens_plotter density_ratios chianti_ne plot_chianti_ne temp_plotter temperature_ratios chianti_te plot_chianti_te freefree freebound two_photon plot_populations pop_plot show_pops pop_processes

rad_loss max_temp plot_ioneq chianti_dem plot_dem integral_calc ch_read_fits

Table 1: List of main-level routines Synthetic sp ectra Multi-purp ose widget to calculate line intensities, create synthetic sp ectra adding the continuum, tables and various outputs. Calculates a synthetic sp ectrum. Outputs arrays. Plots the sp ectrum created by synthetic and interactively identify lines Calculates a synthetic sp ectrum with an isothermal approximation. Outputs arrays. Creates a synthetic sp ectrum. Works with structures. Line intensities Creates an ascii file with a list of line identifications and intensities. Creates a latex file with a list of line identifications and intensities. Multi-purp ose routine that calculates line intensities (without any abundance factor), and outputs an IDL structure. Multi-purp ose routine that creates ascii and latex files with lists of line identifications and intensities. Takes as input the structure created by CH SYNTHETIC. Line emissivities To compute the emissivities of all lines of a sp ecified ion over given ranges of temp erature and density. Calculates the contribution functions G(T) To compute the G(T) of selected lines. Density-sensitive line ratios A widget routine to allow the analysis of density sensitive ratios. Plots the variation of line intensities with electron density A widget to calculate and plot density sensitive line ratios. Plots density sensitive ratios saved from CHIANTI NE Temp erature-sensitive line ratios A widget routine to allow the analysis of temp erature sensitive ratios. Plots the variation of line intensities with electron temp erature . A widget to calculate and plot temp erature sensitive line ratios. Plots temp erature sensitive ratios saved from CHIANTI TE Continuum calculates the free-free (bremsstrahlung) continuum. calculates the free-b ound continuum. calculates the two-photon continuum. Level p opulations plots the level p opulations To plot nj Aj i/Ne values as a function of Ne . To display p opulations of significant levels in a CHIANTI ion mo del. Outputs to the screen the contributions of the different physical pro cesses to the p opulation of the sp ecified level within an ion. Miscellaneous Calculates the radiative losses Calculates temp erature at max ionisation ratio for an ion. Plots the ionisation equilibrium values for an element. 17 Calculates the Differential Emission Measure DEM(T) using the CHIANTI database, from a given set of observed lines. To plot differential emission measure (DEM) values To compute the atomic data integral for use in column or volume emission measure work. Read standard CHIANTI FITS binary table data containing the output from CH SYNTHETIC and outputs a CHIANTI line intensities structure.


Figure 1: Schematic flow chart showing the main links b etween the high-level routines. POP SOLVER is the core low-level routine that is called by most CHIANTI routines. Note that many CHIANTI routines are now wrapp er routines. For example, now DENSITY RATIOS calls EMISS CALC that in turn calls POP SOLVER. SYNTHETIC and ISOTHERMAL are now wrapp er routines that call CH SYNTHETIC and MAKE CHIANTI SPEC.

18


IDL > xdoc,'ch_synthetic' IDL > doc_library,'ch_synthetic' Another way to quickly see the keywords of a routine is to use: IDL > chkarg,'temperature_ratios ..... ---> Call: pro temperature_ratios,ions,wmin,wmax,tempmin,tempmax,$ temperature,ratio,description,$ density=density,psfile=psfile, $ outfile=outfile,noprot=noprot, $ radtemp=radtemp,rphot=rphot,photons=photons, $ ioneq_file=ioneq_file, abund_file=abund_file, $ VERBOSE=VERBOSE

7

The CHIANTI distribution and installation
1. as an indep endent package within SolarSoft, a programming and data analysis environment for the solar physics community. See http://www.lmsal.com/solarsoft/ for details on how to download and install the package. The database and the software are organised in a self-contained package $SSW/packages/chianti/ with the following tree structure: dbase/ doc/ idl/ setup/ (database) (documentation, in particular the USER GUIDE) (IDL software) (supplementary setup files)

CHIANTI is currently distributed in two ways:

The contents of the SolarSoft CHIANTI package are mirrored daily from a master tree. Normally, only small fixes to the existing software can o ccur rather frequently. All mo difications to the software are logged in the $SSW/packages/chianti/idl/HISTORY file. Mo difications to the database are much less frequent. They are describ ed in the $SSW/packages/chianti/dbase/README_CHIANTI file. 19


We send an e-mail to the CHIANTI user group every time we make a minor release of the database available. Note that the contents of the SolarSoft package change on a frequent timescale normally to fix bugs caused by the use of new IDL releases. We recommend that you use CHIANTI within the SolarSoft framework and that you setup in your site a mirror in order to have automatic upgrades. It is easy to follow the instructions to download and setup the package. 2. On the WWW, as tar files, via one the WWW CHIANTI pages, e.g.: · RAL, UK: http://www.chianti.rl.ac.uk/ · NRL, USA: http://wwwsolar.nrl.navy.mil/chianti.html Currently, the data and the software are distributed in two separate tar files. The tar files have a similar tree structure as the SolarSoft distribution. CHIANTI 4.0 pro.tar contains doc/, a copy of $SSW/packages/chianti/doc/ and idl/, a copy of $SSW/packages/chianti/idl/, plus idl/gen/, a copy of the $SSW/gen/ routines. This is b ecause some routines of the $SSW/gen/ directory are needed to run some of the CHIANTI programs. CHIANTI is a package, in the sense that database and progams are to b e used together. The current version of the database must b e used with the current version of the programs. Backward compatibility do es not always apply.

E.g. the data are in CHIANTI 4.0 data.tar that contains a copy of $SSW/packages/chianti/dbas

7.1

Installing CHIANTI

To run any CHIANTI IDL pro cedure, the following is needed: · Access to the CHIANTI IDL routines. The IDL !PATH should contain the paths to the directories where the CHIANTI IDL pro cedures are. · Access to the CHIANTI atomic database and ancillary data. This is done by defining the system variable !xuvtop, that should p oint to the CHIANTI atomic database top directory. · The following IDL system variables need to b e defined: ­ !xuvtop the top directory for the atomic database ­ !ioneq_file the default ionization equilibrium file ­ !abund_file the default elemental abundance file ­ !BCOLOR , !ASPECT

20


7.1.1

Installing CHIANTI within SolarSoft

If you are using SolarSoft you should have the setup already organised so as to have the path of the CHIANTI IDL pro cedures added to IDL PATH, the !xuvtop and the other IDL system variables defined. This is done automatically by using unix> unix> or unix> IDL > setssw chianti sswidl sswidl ssw_packages,/chianti

After this, you will b e able to run the CHIANTI routines. 7.1.2 Installing CHIANTI indep endently as a stand-alone

Users of previous versions, please NOTICE: The pro cedures to install CHIANTI have changed in small but imp ortant ways. Download the CHIANTI files Download the CHIANTI data tar file (e.g. CHIANTI 4.0 data.tar.gz) and the CHIANTI IDL pro cedures tar file (e.g. CHIANTI 4.0 pro.tar.gz) and put the tar files into a directory (for example, /data1/chianti/dbase for the data and /data1/chianti/ for the software) and then do the following: unix> gunzip [file_name].tar.gz unix> tar xvf [file_name].tar This will copy all the CHIANTI data files into /data1/chianti/dbase and create the /data1/chianti/idl and /data1/chianti/do c/ directories. Define the IDL paths and the system variables There are two ways of doing the ab ove. The first is to define the system variables within IDL, the second is outside IDL. We suggest the first option. Once IDL is started, there are three steps: unix > idl

1. add to the IDL PATH the path of where the CHIANTI IDL routines are: Unix: IDL> !PATH = '+/data1/chianti/idl:'+!PATH Windows: IDL> !PATH = '+C:\data1\chianti\idl;'+!PATH VMS: IDL> !PATH = '+/data1/chianti/idl,'+!PATH 21


2. IDL> !PATH = EXPAND_PATH(!PATH) The '+' and the EXPAND PATH are needed since the IDL routines are organised into sub directories. The second option involves writing (UNIX) the following statement in your /.cshrc (or /.login) file: setenv IDL_PATH /usr/local/rsi/idl_4/lib:+/data1/chianti/idl (assuming you have the main IDL directory in /usr/lo cal/rsi/idl 4). 3. Unix: IDL> use_chianti, '/data1/chianti/dbase' Windows: IDL> use_chianti, 'C:\data1\chianti\dbase' After following the ab ove steps, it will b e p ossible to run the CHIANTI routines from any directory. use_chianti also allows you to set your default abundance and ionization equilibria files with the abund and ioneq keywords. Previous CHIANTI users should check the note b elow. We suggest that you add the three ab ove calls to your IDL STARTUP file (say /.idl startup). If this file do es not exist then it should b e created. In UNIX, this can b e done if you add the following line to your .login file: setenv IDL_STARTUP ~/.idl_startup (Note that the changes to the .login file mean that you should do a source ~/.login b efore running IDL). Alternatively, you can write the three statements ab ove in a file, say start_chianti.pro: !PATH = '+/data1/chianti/idl:'+!PATH !PATH = EXPAND_PATH(!PATH) use_chianti, '/data1/chianti/dbase' END

and run IDL> .r start_chianti

Note to previous CHIANTI users: If you had already defined the CHIANTI system variables b efore entering IDL or in your IDL STARTUP file you should remove those definitions. Alternatively, instead of using use_chianti, '/data1/chianti/dbase', you have to make sure you have in your IDL STARTUP file something like this:

22


!PATH = '+/data1/chianti/idl:'+!PATH !PATH = EXPAND_PATH(!PATH) defsysv,'!xuvtop', '/data1/chianti/dbase' defsysv,'!ioneq_file','/data1/chianti/dbase/ioneq/mazzotta_etal.ioneq' defsysv,'!abund_file','/data1/chianti/dbase/abundance/cosmic.abund' defsysv,'!BCOLOR',0 defsysv,'!ASPECT',1.0

23


8
8.1

Theory and definitions
Optically thin emission lines

For a review on Spectroscopic Diagnostics in the EUV for Solar and Stel lar Plasmas see e.g. Mason and Monsignori Fossi (1994). c The intensity I (ij ), of an optically thin sp ectral line of wavelength ij (frequency ij = hij ) is hij Nj Aj i dh [ergs cm-2 s-1 sr-1 ] (1) 4 where i, j are the lower and upp er levels, Aj i is the sp ontaneous transition probability, Nj is the numb er density of the upp er level j of the emitting ion and h is the line of sight through the emitting plasma. In low density plasmas the collisional excitation pro cesses are generally faster than ionization and recombination timescales, therefore the collisional excitation is dominant over ionization and recombination in p opulating the excited states. This allows the low-lying level p opulations to b e treated separately from the ionization and recombination pro cesses. For allowed transitions we have Nj (X +m )Aj i Ne . The p opulation of the level j can b e expressed as: I (ij ) = Nj (X
+m

Nj (X +m ) N (X +m ) N (X ) N (H ) N )= N (X +m ) N (X ) N (H ) Ne

e

(2)

· N (X +m )/N (X ) is the ionization ratio of the ion X +m relative to the total numb er density of element X (contained in the files in the ioneq/ directory); · Ab(X ) = N (X )/N (H ) is the elemental abundance relative to Hydrogen (contained in the files in the abundance/ directory); · N (H )/Ne is the Hydrogen density relative to the free electron density. Often assumed to b e equal to 0.83, as hydrogen and helium are usually completely ionised for hot optically thin plasmas. See the routine PROTON DENS describ ed in Sect. B.5 for details on how to calculate N (H )/Ne . · The fraction ni = Nj(X +m ) of ions X+m lying in the state j is determined within CHIANTI by solving the statistical equilibrium equations for a numb er of low-lying levels of the ion including all the imp ortant collisional and radiative excitation and de-excitation mechanisms. In the `standard mo del' for interpreting line intensities there are three fundamental assumptions that serve to simplify the problem considerably: 1. the plasma is in a steady state;
N (X
+m

)

24


2. atomic pro cesses affecting the ionisation state of an element can b e separated from those affecting the level balance within an ion; 3. all lines are optically thin. The atomic data contained in the CHIANTI database are particularly suited to the analysis of emission lines via this mo del, and the following discussion outlines this approach. No attempt is made to discuss non-equilibrium conditions. With the first of the assumptions, the p opulation of ions lying in a given state is constant and so the numb er of ions leaving this state p er unit time must exactly balance the numb er arriving into that state. If we denote the numb er of transitions leaving the state i to a state j taking place p er unit time p er unit volume by ij , then steady state implies N Setting ii = -
j=i i j=i

ij =
j=i

Nj ji .

(3)



ij

(4)

we have Nj ji = 0
j

(5)

for each state i and, as the co efficients ji are indep endent of the state p opulations, we have a set of linear equations to solve for the Ni . Now our second assumption means that the pro cesses that affect the ionisation state of the plasma do not affect the quantity ni . Eq. 5 thus b ecomes nj ji = 0
j

(6)

where the ji only include those pro cesses that affect the level balance of the ion. For the basic CHIANTI mo del these pro cesses are simply electron and proton excitation and de-excitation, and the generalised radiative decay:
p e ij = Ne Cij + Np Cij + A ij

(7)

p e where Cij is the electron excitation­de-excitation rate, Cij is the proton excitation­deexcitation rate, Np is the proton density, Aij is the generalized radiative decay rate, that includes Aij , the radiative decay rate which is zero for i
e Cij = N

e

j E q exp i kT

ji

i>j

(9)

25


where i is the statistical weight of level i, k is Boltzmann's constant, T the electron temp erature, and qij the electron excitation rate co efficient which is given by: qij = 2.172 â 10
-8

I kT

1/2

exp -

E kT

ij i

[cm3 s-1 ]

(10)

where I is the Rydb erg energy (13.61 eV), and ij is the thermally-averaged collision strength for the i j excitation. The ij are derived from the scaled data in the CHIANTI .splups files. The solution of Eq. 6 is p erformed by the CHIANTI routine pop_solver.pro, which gives the fraction of ions in the state i. The level p opulations for a given ion can b e calculated and displayed with plot_populations.pro (but also see pop_plot.pro). We rewrite the intensity as: I (ij ) = where the function hij Aj i Nj (X +m ) N (X +m ) [ergs cm+3 s-1 ], (12) +m ) 4 Ne N (X N (X ) called the contribution function, contains all of the relevant atomic physics parameters and is strongly p eaked in temp erature. gofnt.pro calculates these contribution functions (see also g_of_t.pro for a slightly different way of calculating contribution functions). Please note that in the literature there are various definitions of contribution functions. Aside from having values in in either photons or ergs, sometime the factor 41 is not included. Some times a value of 0.83 for N (H )/Ne is assumed and included. Sometimes the element abundance factor is also included. Any of the ab ove (or any other) variations also affect the definition of a line intensity in terms of the contribution function and the DEM. In the following we will refer to the functions C (T , ij , Ne ) and G(T , ij , Ab(X ), Ne ) = Ab(X ) C (T , ij , Ne ) ( i.e. the contribution function that contains the abundance factor ). If we define, assuming that is a single-value function of the temp erature, the differential emission measure D E M (T ) function as C (T , ij , Ne ) = dh [cm-5 K-1 ] (13) dT the intensity can b e rewritten, assuming that the abundance is constant along the line of sight: D E M (T ) = Ne N
H

Ab(X )C (T , ij , Ne )Ne NH dh

(11)

I (ij ) = Ab(X )
T

C (T , ij , Ne ) D E M (T ) dT

[ergs cm

-2

s

-1

sr-1 ]

(14)

The the The sion

DEM gives an indication of the amount of plasma along the line of sight that is emitting radiation observed and has a temp erature b etween T and T + dT . IDL routine chianti_dem.pro describ ed in Sect. 9.16 calculates the Differential EmisMeasure DEM(T) using the CHIANTI database, from a given set of observed lines. 26


Routines such as ch_synthetic.pro (see Sect. 9.1 and Sect. ??) calculate line intensities without the abundance factor, that is only included at a later stage. In the isothermal approximation, all plasma is assumed to b e at a single temp erature (To ) and the intensity b ecomes: I (ij ) = C (To , ij , Ne )Ab(X )E M where we have defined the column emission measure E Mh = Ne NH dh [cm-5 ] (16)
h

(15)

ch_synthetic.pro in the isothermal approximation calculates I = C (T o , ij , Ne ) Ne NH dh, while isothermal.pro and ch_ss.pro (see examples in Sect. 9.1) can b e used to create synthetic sp ectra (with the abundance factor). It is also p ossible to calculate intensities and sp ectra with a multi-temp erature mo del, by providing an array of To , E Mh values. Please note that in the literature many different definitions of Differential Emission Measures, Emission Measures and approximations can b e found (see Del Zanna et al., 2002 for some clarifications). 8.1.1 The stellar case

In the stellar case, the theoretical flux of an optically thin sp ectral line is: 1 Ab(X ) C (Ne , T , ij ) Ne N H dV [ergs cm-2 s-1 ] (17) 2 dV where C (Ne , T , ij ) has the same expression as ab ove, d is the star's distance, dV is the volume element, and V is the entire source volume. A volume Differential Emission Measures D E M is often defined: dV [cm-3 K-1 ] (18) D E M (T ) = Ne NH dT together with a corresp onding volume emission measure E MV : F (ij ) = E MV = Ne NH dV [cm-3 ] (19)

At the moment CHIANTI do es not include volume emission measures. In the near future we will mo dify the software and the definition of the D E M in order to include volume emission measures. However, any volume Differential Emission Measures can b e rescaled to column D E M s and used within the software to pro duce synthetic sp ectra for stellar coronae. One way of doing this is to assume spherical symmetry, and that the emitting region is a layer dh 2 distributed over the entire star's disk, i.e. dV = 4 R dh (R is the star's radius). If the 2 star's radius and distance are known, a volume D E M can b e scaled with the factor 4R d2 to obtain a column D E M . If this is used, the outputs will have flux units, i.e. er g scm-2 s-1 (or photonscm-2 s-1 ) and not er g scm-2 s-1 sr -1 . 27


An example of scaled D E M is provided in the file AU Mic.dem, in the CHIANTI distribution. Column D E M s and E M s are assumed when the sp ectra are folded with effective areas (see Sect. 9.1). The effective areas are assumed to have units of countsphotons -1 cm+2 , so the output units of the sp ectra will b e countss-1 pixel-1 . Also note that corrections to interstellar absorption are not presently included in CHIANTI.

8.2

Proton rates

For each ion for which proton rates are available, an additional file is required in the database to contain the fits to the rate co efficients. The file has the suffix .PSPLUPS, and is exactly analogous to the .SPLUPS file for the electron fits. All of the proton transitions included in CHIANTI are forbidden transitions taking place b etween levels within the same configuration. Many of the transitions required 9-p oint splines (see Sect. C) in order to provide adequate fits. The numb er density of protons, Np , is calculated with the IDL routine proton_dens.pro (see Sect. B.5). By default, all routines will include proton rates in the calculation of the ion level balance. A keyword /NOPROT can b e used to switch off the proton rates.

8.3

Non-Maxwellian particle distributions

Within CHIANTI the assumption of Maxwellian electron and proton distributions is implicit through the storage of Maxwellian-averaged electron and proton collision strengths in the .SPLUPS and .PSPLUPS data files. To mo del emission from plasmas with general, nonMaxwellian particle distributions would require integrations of the original collision strengths with the new particle distributions, and this is outside of the scop e of the CHIANTI database. However, if the particle distributions can b e expressed as a linear combination of Maxwellians of different temp eratures, i.e., f (E ; ai ) =
i

ai fM (E , Ti )

(20)

where the Maxwellian function fM (E , Ti ) is given by E 1/2 1 3/2 E exp - (21) kT kT then such distributions can b e mo delled in a straightforward manner within the CHIANTI framework. The generalized electron excitation rate co efficient for the transition j to k and for the particle distribution f of electron velo cities is given by fM (E , Ti ) = 2


C

jk

= =

E

Qj k v f (E ; ai )dE
jk

(22) (23)



a
i

i

E

Qj k v fM (E , Ti )dE
jk

28


=
i

ai Cj k (Ti )

(24)

where Ej k is the threshold energy for the transition, Qj k is the collision cross section, E (= me v 2 /2, me the electron mass) is the energy of the incoming electron, and Cj k (Ti ) is the electron excitation rate co efficient for a Maxwellian particle distribution of temp erature T i (see, e.g., Burgess & Tully 1992). The matrix Cj k replaces the usual Maxwellian-derived rate co efficient (Cj k ) in the level balance equations solved by the CHIANTI software. The software routines for calculating emissivities and level p opulations have b een mo dified to allow input of the non-Maxwellian parameters ai through the keyword SUM MWL COEFFS. The temp eratures Ti are sp ecified through the standard temp erature input to the routines. The temp eratures are assumed to apply to b oth proton and electron distributions. This prescription for treating non-Maxwellian distributions is not compatible with the treatment of ionization and recombination since an equilibrium ionization balance describ ed by a single temp erature is required for these pro cesses. In such cases the ionization and recombination pro cesses describ ed in Sect. ?? are switched off when calculating the level p opulations if the ai co efficients are sp ecified in CHIANTI. See Sect. 9.8 for an example.

8.4

Photo excitation and Stimulated Emission

Within CHIANTI, we presently mo del the Photo excitation and Stimulated Emission by assuming a a blackb o dy radiation field of temp erature T . The generalized photon rate co efficient in this case is:


W (R)A A
ji

j 1 j i i exp(E /k T )-1 1 exp(E /k T )-1

ij

Aij =

1 + W (R)

where Aj i is the radiative decay rate and W (R) is the radiation dilution factor which accounts for the weakening of the radiation field at distances R from the source center. We also assume an uniform (no limb brightening/darkening) spherical source with radius R : W= where R (27) R It is imp ortant to rememb er the assumptions in our formalism for radiation pro cesses. For a given ion, only very sp ecific wavelengths in the radiation continuum will affect the ion's level balance. If there are significant deviations from a blackb o dy sp ectrum at any of these wavelengths (p erhaps due to a deep absorption line) then CHIANTI do es not mo del the ion entirely correctly. r= 29 1 1 1- 1- 2 2 r
1/2

(26)


Examples of sp ecific uses of the extra radiation pro cesses include mo deling of lines ab ove the surface of the Sun and other co ol stars when the coronal falls to low enough values that electron collisions lose their p otency. For the Sun, photo excitation is very imp ortant for the infrared coronal lines. is also imp ortant for mo delling nebular ions that are irradiated by a hot planetary nebulae, symbiotic stars and Wolf-Rayet stars. 8.4.1

coronal emission electron density Photo excitation star, such as in

Implementation of Photo excitation and Stimulated Emission

No additions or mo difications to CHIANTI data files are required for photo excitation and stimulated emission as their rates are entirely determined from the radiative decay rates, level separation energies, and statistical weights ­ information already contained in CHIANTI. It is only necessary to sp ecify the radiation field temp erature and the dilution factor. These are sp ecified as inputs to the IDL pro cedures through the new keywords RPHOT R and RADTEMP. RPHOT sp ecifies r = R , while RADTEMP gives the blackb o dy radiation temp erature in K. By default, photo excitation and stimulated emission are not included in the level balance equations unless the keywords are set.

8.5

Photo excitation by arbitrary radiation fields

Version 4 of CHIANTI intro duced the p ossibility of including photo excitation and stimulated emission through an external blackb o dy radiation field into the level balance equations. With version 5 the software has b een mo dified to allow an arbitrary, user-defined radiation field to b e sp ecified. The user must create an IDL routine that calculates the energy density p er unit wavelength, U , as a function of wavelength. The photo excitation rate for a transition i j is related to U by the expression Pij = Aj i W (R) j 5 U i 8 hc


(28)

where W (R) is the dilution factor defined as in Young et al. (2003), Aj i is the Einstein co efficient for sp ontaneous radiation from j to i, j and i are the statistical weights of levels j and i. or example, U for a blackb o dy of temp erature, T , is given by U
bb

=

8 hc 1 5 exp(hc/k T ) - 1

(29)

thus giving the photo excitation rate for a blackb o dy of P
bb ij

= Aj i W (R)

j 1 i exp(E /k T ) - 1 c U . 4 30

(30)

For reference we note that the energy density is related to the sp ecific intensity, I , by I = (31)


The user-defined radiation field function is implemented through a keyword RADFUNC='user function, a, b' in the CHIANTI IDL routines SHOW POPS and EMISS CALC. The optional co efficients a and b can b e used to mo dify the radiation field, e.g., by sp ecifying a relative velo city b etween the radiation field and incident ion. See Sect. 9.7 for an example.

8.6

Ionization and recombination

In Version 5 of CHIANTI, we have included ionization and recombination into level p opulations. The CHIANTI mo del for ionization and recombination assumes that the plasma can b e describ ed under the Coronal Mo del Approximation, where the total p opulation of the excited levels of an ion is negligible compared to the p opulation of the ground level. In this case, recombination and ionization pro cesses can b e included in a relatively straightforward way, since they can b e treated as a correction to the case where p opulations are calculated neglecting them. To illustrate this metho d, we will consider the simplified atomic mo del of an ion X +q with abundance nq comp osed of the ground level and one excited level only. In case ionization and recombination contributions to level p opulations are negligible, the relative p opulation of the upp er level is obtained by solving the equation: Ng Ne C
g i

= Ni A

ig

=

Ni Ng

=
ion/r ec

Ne Cgi Aig

(32)

where Cgi is the collisional excitation rate and Aig is the Einstein co efficient for sp ontaneous radiative decay. Collisional de-excitation is neglected in the coronal mo del approximation. In case ionization and recombination provide significant contribution, Equation 32 needs to b e mo dified to include the rate co efficients for ionization (ion ) and recombination (rec ): Ng Ne (nq C
g i

+n

q -1 ion

+n

q +1



r ec

) = Ni A

ig nq q +1

(33) , resp ectively. The

where nq-1 , nq , nq+1 are the ion fractions for the ions X q-1 , X q and X p opulation of the excited level can then b e expressed as Ni Ng Ni Ng

=
ion/r ec

â
no ion/r ec

(34)

where the correction is given by = 1+ n
q -1



ion

+ nq+1 nq Cgi

r ec

(35)

The correction is temp erature sensitive and can b e large when the collisional excitation rate is small or when the abundance of the ion q is much smaller than the abundances of the adjacent ions. The correction due to ionization and recombination can have significant effects on intensities of observed X-ray lines. 31


The only limitation of this approach lies in the breakdown of the coronal mo del approximation at high densities for a few ions. This o ccurs at densities ab ove which metastable level p opulations b egin to b e non-negligible, compared to the ground state (cf. Landi et al. 2005). The CHIANTI software has b een mo dified to allow calculation of the correction factor for the ions for which ion and rec are provided. The inclusion of ionization and recombination effects in level p opulation has required some more changes. New files have b een created (.CILVL and .RECLVL) to store the ionization and recombination rates necessary for this pro cess (see Sect. 5.1.1 for details). A new routine (READ IONREC.PRO) has b een created to read these files and store their data in the input to the routine POP SOLVER.PRO. This latter routine has b een mo dified to include the correction to the level p opulations. In case the .CILVL and .RECLVL files are not available, a flag is set in the programs and these pro cesses are ignored. The impact of this new pro cess on the running time is negligible. However, the intro duction of ionization and recombination effects on level p opulation has had a side effect. In previous versions of CHIANTI, the contribution to the intensity of sp ectral lines from levels b elow the ionization p otential due to cascades from levels ab ove the ionization p otential was taken into account in the "dielectronic" .WGFA files, which included radiative transitions from the former, p opulated by cascades from the latter. For the ions for which the complete .RECLVL and .CILVL files are now available (Fe XVI I to Fe XXIV), cascades from levels ab ove ionization are now taken into account directly, so that the cascade contribution calculated by the "dielectronic" .WGFA files is not anymore necessary. To avoid double-counting this contribution, the transitions from levels b elow the ionization threshold in the "dielectronic" .WGFA files have b een given a null wavelength, so they can b e removed from the sp ectrum without having to change the way the "dielectronic" level p opulation are handled.

8.7

Continuum calculations

An IDL routine to include the two photon continuum has b een added to CHIANTI, while the free-b ound and free-free continuum (bremsstrahlung) routines have b een revised. See Young et. al. (2002) for more details. Note that the output units of the continuum routines are by default 10-40 A ergs sr-1 s-1 °-1 p er unit emission measure Ne NH dh. On the other hand, the SolarSoft routine CONFLX outputs a continuum in 2 A photons s-1 °-1 assuming an emission measure Ne dh = 1050 . 8.7.1 Two photon continuum

The two-photon continuum is calculated with two_photon.pro. Transitions in hydrogen-sequence ions The first excited level (2s 2 S1/2 ) of the hydrogen iso-electronic sequence ions can decay only by means of forbidden magnetic dip ole and two-photon transitions. The imp ortance

32


of the comp eting magnetic dip ole transition increases with Z but for nickel (Z = 28), the two-photon transition rate is roughly 5 times that of the magnetic dip ole rate. The sp ectral emissivity (erg cm-3 s-1 sr-1 °-1 ) for optically-thin two-photon emission at A wavelength is given by: hc d i,j = Aj i Nj (X +m )(0 /) (36) d 4 where Aj,i (sec-1 ) is the Einstein sp ontaneous emission co efficient (A value); Nj (X +m ) is the numb er density of the level j of the ion X +m ; is the sp ectral distribution function; and 0 is the wavelength corresp onding to the energy difference b etween the excited and ground level. Two-photon continuum transitions in helium-sequence ions For the helium iso-electronic sequence, the second excited level (1s2s 1 S0 ) decays through a forbidden magnetic dip ole and two-photon transitions. 8.7.2 Bremsstrahlung

The bremsstrahlung emission is calculated with freefree.pro. This routine has b een rewritten ex-novo. It now includes the Itoh et al. (2000) and Sutherland (1998) gaunt factors. Itoh et al. (2000) have provided an analytical fitting formula for the relativistic thermal bremsstrahlung gaunt factors, and this is now added to CHIANTI. The fitting formula is valid for the ranges 6.0 log T 8.5 and -4.0 log (hc/k T ) 1.0. For temp eratures b elow log T = 6.0 we retain the non-relativistic Gaunt factors of Sutherland (1998) for computing the continuum. The condition log (hc/k T ) 1.0 results in some of the low wavelength p oints b eing inaccurately represented by the Itoh et al. fitting formula. For these wavelengths the Gaunt factors of Sutherland (1998) are used to compute the continuum level. The relativistic free-free continuum is almost identical to the non-relativistic continuum at low temp eratures. At T = 1 â 108 K (the maximum temp erature p ermitted by the ion balance calculations contained in CHIANTI) the relativistic continuum is around 1% higher near the p eak of the distribution. 8.7.3 Free-b ound continuum

The free-b ound continuum emission is calculated with freebound.pro. This routine has b een rewritten. The new routine uses the the Karzas and Latter (1961) approximation to the photoionization cross-sections and calculates free-b ound gaunt factors for levels n=1-6. Additional data files have b een created for this purp ose. For example, free-b ound radiation pro duced by recombination of an electron onto C IV to pro duce C I I I will use the data in the c\_3.fblvl file.

33


9

Some examples on how to use the software

In what follows we review the main p oints ab out the new software. We hop e you find it useful and enjoy using it !

9.1

Calculating line intensities.

For an user-friendly, widget-based approach the b est option is to use CH SS: IDL >ch_ss This widget allows the user to calculate synthetic sp ectra in two basic steps. Basically, you follow the various widgets from top left to lower right to set the desired parameters. First calculate the line intensities. These values can b e saved for later use. Next, sp ecify further parameters such as the elemental abundances and instrumental sp ectral resolution and then calculate and plot the sp ectrum. These values can also b e saved for later use. The HELP buttons in the widget provide short descriptions of the required information. More details are given b elow. Alternatively, for e.g. background jobs, the routine CH SYNTHETIC can b e used. ch_synthetic.pro calculates line intensities assuming constant pressure or density (or a mo del T,N), without the abundance factor. One of the reasons why element abundances are not included in the line intensities calculation is so that it is easier for the user to see how mo difying abundances affects their sp ectra in e.g. ch_ss.pro. The calling sequence is: IDL> ch_synthetic, wmin, wmax, output=output, err_msg=err_msg, msg=msg, $ pressure=pressure, density=density, $ model_file=model_file, all=all,sngl_ion=sngl_ion, $ photons=photons, masterlist=masterlist, $ save_file=save_file , verbose=verbose,$ logt_isothermal=logt_isothermal, logem_isothermal=logem_isothermal,$ goft=goft, ioneq_name=ioneq_name, dem_name=dem_name, $ noprot=noprot, rphot=rphot, radtemp=radtemp, progress=progress The routine has many KEYWORDS (see Sect. ?? for a full list) A series of parameters must b e set: · Wmin, Wmax: minimum maximum of the desired wavelength range in Angstroms

· The (Te,Ne) mo del for the calculation: Pressure: pressure in emitting region (Pe, cm^-3 K). Only a single value is accepted, and the calculation is performed at constant pressure. density in emitting region (Ne, cm^-3). Only a single value is accepted, and the calculation is 34

Density:


performed at constant density, unless LOGT_ISOTHERMAL is defined. In this case, DENSITY can be an array of values, but has to have the same number of elements as LOGT_ISOTHERMAL.

model_file

Full path of the (Te,Ne) This file should have two values, and one with the values are not sorted in routine does sort them.

file if defined. columns, one with the Te (K) Ne (cm^-3) values. If these ascending order of Te, the

· IONEQ NAME: The ionization fraction file to b e used. The program will prompt the user to select one if not defined. · OUTPUT: The name of the structure containing the line intensities and details. The line intensities are calculated either in the isothermal approximation, in which case the following has to b e defined: LOGT_ISOTHERMAL: LOGEM_ISOTHERMAL: Array of logarithmic temperatures. Array of logarithmic emission measures (0 by default).

or by folding the G(T ) with a differential emission measure D E M contained in the file sp ecified by DEM NAME. The program will prompt the user to select one if not defined. Example: IDL> ch_synthetic, 10,20., output=str , pressure=1.e+15,$ ioneq_name=concat_dir(concat_dir(!xuvtop,'ioneq'),'mazzotta_etal.ioneq'),$ dem_name=concat_dir(concat_dir(!xuvtop,'dem'),'flare.dem'),$ /photons, /noprot, /all, sngl_ion=['fe_17','fe_18'] Creates an output structure str that contains the line intensities of only Fe XVI I and Fe XVI I I in the 10­20 ° range calculated at constant pressure of 1015 , with the ionization A balance in mazzotta_etal.ioneq and the D E M values in flare.dem in the standard CHIANTI distribution (if not supplied these files can b e selected with a widget). Line intensities are in photons cm-2 s-1 sr-1 (KEYWORD photons), the proton rates are not included (KEYWORD noprot), and all the lines in the database (KEYWORD all) are included (also the lines with only theoretical energy levels). You can see the contents of the structure with e.g. IDL> help, str,/st IDL> help, str.lines[0],/st The last command shows the first structure asso ciated with the first sp ectral line.

35


9.2

Saving, restoring and exp orting the CHIANTI line intensities structure

The CHIANTI line intensities structure can b e saved and later restored from the command line in various ways. We suggest two: 1. as IDL binary files using the SolarSoft routines: IDL> savegen, file='ch_int_10_20_fe.genx', struct=str IDL> restgen, file='ch_int_10_20_fe.genx', struct=str to save and restore the IDL structure str in the file ch_int_10_20_fe.genx. Please note that we discourage the use of e.g.: IDL> save, file='output.save', output IDL> restore, file='output.save' since IDL save files generated with later versions of IDL are usually not readable with earlier versions. 2. as FITS binary tables, that can b e easily exp orted and read by different platforms. We have written two IDL routines: IDL> ch_write_fits, str, 'output.fits' IDL> ch_read_fits,'output.fits', str to save and restore the IDL structure str in the FITS file output.fits. Aside from an intro ductory HEADER, the contents of the IDL structure are converted into two binary tables. Extensive comments are added. In either case, the structure saved in the .genx and .fits files can b e restored via CH SS to later create a sp ectrum.

9.3

Create a latex or ascii file with all the line details

For an user-friendly approach the b est option is to use CH SS: IDL >ch_ss Alternatively, if you have already calculated a line intensity structure (as shown ab ove), you can use CH LINE LIST. This program creates a latex or an ascii file of predicted sp ectral line intensities and wavelengths corresp onding to selected parameters. The routine has many KEYWORDS. Please read the header or read Sect. ?? for details. The calling sequence is: 36


IDL> ch_line_list, transitions, outname, latex=latex, ascii=ascii, $ wmin=wmin,wmax=wmax,$ SPECTRUM=SPECTRUM, abundfile=abundfile, min_abund=min_abund, $ minI=minI,photons=photons,kev=kev, $ all=all,no_sort=no_sort, sngl_ion=sngl_ion Example: IDL> restgen, file='ch_int_10_20_fe.genx', struct=tran IDL> ch_line_list, tran, 'ch_line_list.tex', /latex,$ abundfile=concat_dir(concat_dir(!xuvtop,'abundance'),'cosmic.abund'),$ mini=1e13 This creates a latex file ch_line_list.tex where only lines with an intensity greater than 1013 (KEYWORD mini) are included, and the allen.abund file in the standard CHIANTI distribution is used (if not supplied it can b e selected with a widget). Then, you have to latex the file three times, and optionally xdvi it: unix> unix> unix> unix> latex latex latex xdvi ch_line_list ch_line_list ch_line_list ch_line_list

If you do not have it already, you will need the package longtable.sty that is distributed as part of ftp://cam.ctan.org/tex-archive/macros/latex/required/tools.tar.gz You will obtain a table that lo oks like: Table 2: Line List Ion Fe XVI Fe XVI Fe XVI Fe XVI Fe XVI (° A) 12.1227 12.2639 13.8231 13.9540 14.1519 Transition 2p6 1 S0 - 2p5 4d 1 P1 2p6 1 S0 - 2p5 4d 3 D1 2p6 1 S0 - 2s 2p6 3p 1 P1 2s2 2p5 2 P3/2 - 2p4 (1 S) 3d 2 D5/2 2s2 2p5 2 P3/2 - 2p4 (1 D) 3d 2 D3/2 Tmax 6.9 6.9 6.9 6.9 6.9 Int 1.11e+14 9.81e+13 6.25e+13 2.06e+13 1.35e+13

I I I II II

Alternatively, you can also create a latex file with a list of line identifications and intensities using the wrapp er routine LATEX WVL DEM: IDL > latex_wvl_dem,100.,200., pressure=1.e+15,mini=1. However, latex_wvl_dem calls ch_synthetic and ch_line_list, and if you want to mo dify some of the parameters of ch_line_list (e.g. the minimum intensity) you will have to redo the calculation which will take some time. Windows will p op up so that you can select the abundance, the ionization equilibrium and the differential emission measure files. This will create by default a file linelist.tex in the user's working directory, by default. To create an ascii file with the line details you can follow a similar approach, i.e.: 37


IDL> restgen, file='ch_int_10_20_fe.genx', struct=tran IDL> ch_line_list, tran, 'ch_line_list.ascii', /ascii,$ abundfile=concat_dir(concat_dir(!xuvtop,'abundance'),'allen.abund'),$ mini=1e13 Alternatively, you can also use the wrapp er routine IDL > ascii_wvl_dem,100.,200.,pressure=1.e+15,mini=1. However, ascii_wvl_dem calls ch_synthetic and ch_line_list, and if you want to mo dify some of the parameters of ch_line_list (e.g. the minimum intensity) you will have to redo the calculation which will take some time.

9.4

Calculating continuum intensities

For example, to calculate the free-free, free-b ound and two-photon continuum at a temp erature of 5 â 106 K, for wavelengths at 1 ° intervals b etween 1 and 50 ° A A: freefree,5.e+6,findgen(50)+1.,ff freebound,5.e+6,findgen(50)+1.,fb two_photon,5.e+6,findgen(50)+1.,tp window,0 plot,findgen(50)+1.,ff+fb+tp,xtit='Wavelength (A)' oplot, findgen(50)+1.,ff,line=2 oplot, findgen(50)+1.,fb,line=3 oplot, findgen(50)+1.,tp,line=4 Note that the intensities are in units of 10-40 ergs cm3 s-1 sr-1 °-1 p er unit emission measure A -5 NH Ne dh (cm ). If D E M values are passed to the routines (via the keyword DEM INT), it is assumed that they are given as NH Ne dh/dT . The units are 10-40 ergs cm-2 s-1 sr-1 °-1 in this case. A

9.5

Creating a synthetic sp ectrum with the continuum

The structure created by CH SYNTHETIC can b e restored via CH SS to create a sp ectrum. Alternatively, it can b e used as an input to the program MAKE CHIANTI SPEC. This program creates the CHIANTI SPECTRUM structure (read Sect. E.2 for details), an OUTPUT structure similar to the structure created by CH SYNTHETIC, with some additional tags. The calling sequence is: IDL> make_chianti_spec, TRANSITIONS, LAMBDA, OUTPUT, INSTR_FWHM=INSTR_FWHM, BINSIZE=BINSIZE, $ WRANGE=WRANGE, ALL=ALL, continuum=continuum, ABUND_NAME=ABUND_NAME, MIN_ABUND=MIN_ABUND, photons=photons, file_effarea=file_effarea, err_msg=err_msg, verbose=verbose 38 BIN_SIZE=BIN_SIZE, $ $ $ $


Figure 2: Continuum in the 1-50 ° range. A The routine has many keywords and options. Please read Sect. ?? for details. IDL> restgen, file='ch_int_10_20_fe.genx', struct=tran IDL> make_chianti_spec, tran, lambda, struct,/CONTINUUM, $ BIN_SIZE=0.01, instr_fwhm=0.1, WRANGE=[10.,19.],$ abund_name=concat_dir(concat_dir(!xuvtop,'abundance'),'cosmic.abund')

Figure 3: Synthetic sp ectrum created by MAKE CHIANTI SPEC. 39


Some Caveats: You may find that the calculation is slow. This is usually due to the continuum calculation. In general, it is advisable not to calculate sp ectra over large wavelength ranges. In any case you can sp eed up the continuum calculation by reducing the numb ers of elements, using the KEYWORD MIN ABUND. To see the contents of the structure: IDL> help, struct,/st IDL> help, struct.lines[0],/st While to show the sp ectrum and the main contributing lines: IDL> window,0 & plot,struct.lambda,struct.spectrum for i=0,n_elements(struct.lines) -1 do $ if struct.lines[i].peak gt 7e5 then $ xyouts, struct.lines[i].wvl, struct.lines[i].peak, struct.lines[i].snote It may b e useful to save the SPECTRUM structure, that can b e later insp ected with the widget CH SS: IDL> savegen, file='ch_spectrum_10_20_fe.genx', struct=struct IDL> ch_write_fits, struct, 'ch_spectrum_10_20_fe.fits' Alternatively, the wrapp er routine SYNTHETIC (see Fig 1) can also b e used to calculate CHIANTI line intensities. For example:

IDL > synthetic, 150., 200., 1., pressure=1.e+15, wvl, spectrum, list_wvl, list_ident will create a synthetic sp ectrum with a resolution of 1 ° b etween 150 and 200 ° for a sp ecified A A set of abundances and differential emission measure at a constant pressure of 1.e+15 (N e T cm-3 K). The output arrays wvl, sp ectrum contain the wavelengths and the intensities (in erg cm-2 s-1 sr-1 °-1 by default). The output arrays ist wvl, list ident contain the list of A wavelengths and descriptions of the lines that made up the sp ectrum. Windows will p op up so that the user can select the abundance file, the ionization equilibrium and the differential emission measure. A sp ectrum is created by convolving with a Gaussian profile with a FWHM of 1 ° If the /CONTINUUM keyword had b een set, then A. the continuum would also have b een calculated and added to the sp ectrum. To plot the sp ectrum and interactively identify lines: IDL > synthetic_plot, wvl, spectrum, list_wvl, list_ident, 2. ° by clicking the left mouse button, a list of predicted lines within 2 A of the selected wavelength will b e printed out along with their predicted intensity. Clicking the right mouse button will exit the pro cedure.

40


9.5.1

Create a sp ectrum in the isothermal approximation

For an user-friendly approach the b est option is to use CH SS: IDL >ch_ss Alternatively: IDL > isothermal, 150., 200., 1., [1.e6], wvl, spectrum,$ list_wvl, list_ident, edensity=1.e9,$ ioneq_name=!xuvtop+'/ioneq/mazzotta_etal.ioneq',$ abund_name=!xuvtop+'/abundance/cosmic.abund' IDL> synthetic_plot, wvl, spectrum, list_wvl, list_ident, 1.

calculates an isothermal synthetic sp ectrum with a resolution of 1 ° b etween 100 and 200 ° A A for a sp ecified set of abundances and differential emission measure at a constant density Ne = 109 cm-3 . The output arrays wvl, sp ectrum contain the wavelengths and the intensities (in erg cm-2 s-1 sr-1 °-1 by default). The output arrays ist wvl, list ident contain the list A of wavelengths and descriptions of the lines that made up the sp ectrum. synthetic_plot can then b e used to view the sp ectrum. Note: isothermal now is a wrapp er routine that calls ch_synthetic . It has particular features. Please read the header do cumentation.

9.6

The user-friendly multi-purp ose widget ch ss.pro

CH SS is an user-friendly multi-purp ose (see Fig 1) widget that allows the calculation of line intensities (calling CH SYNTHETIC) and of a synthetic sp ectrum (calling MAKE CHIANTI SPEC) by merging line intensities and continua. The parameters can b e interactively set, and the results visually insp ected. Line intensities can b e saved and restored in various ways. The results can also b e stored in various ways, ranging from output plots to tables of line details (using CH LINE LIST) or save files. CH SS replaces the CHIANTI SS pro cedure. The calling sequence is: IDL> ch_ss, font=font Note that if the widget app ears to o large you can change the font. The widget is organised into four Sections: 9.6.1 SECTION 1 - The Calculation of the CHIANTI line intensities.

This can b e done in two ways: 1-Restore a save file with the CHIANTI line intensities already calculated. This is done with the RESTORE button. .genx and .fits files can b e restored. 2-Calculate CHIANTI line intensities with a call to CH SYNTHETIC. In this case, A series of parameters must b e set: 41


Figure 4: The multi-purp ose widget CH SS · - Minimum and maximum wavelengths in Angstroms · - The mo del used for the calculation. Three are the options: 1) a constant density (cm-3 ) 2) a constant pressure (cm- 3 K) 3) a general (Te,Ne) mo del. In this case, a file will b e read. This file should have two columns, one with the Te (K) values, and one with the Ne (cm-3 ) values. · - The ionization fraction file to b e used. "*.ioneq" files can b e selected from either the CHIANTI database, the working directory or selected via a widget. · - All ions ? If set to yes (default), then all the ions present in the database will b e included. If set to no, then it is p ossible to select a list of ions with a widget · - All lines ? If set to no (default), only the lines for which there are observed energy levels are included 42


If set to yes, also the lines that do not have corresp onding observed energy levels are included. In this case, the wavelengths are calculated from the theoretical energy levels, and might not b e very accurate. · - Isothermal ? If set to no (default), a DEM file must b e selected. "*.dem" files (i.e. files with a .dem extension) can b e selected from either the CHIANTI database, the working directory or selected via a widget. If set to yes, then the user is requested to enter one or more temp eratures (as logarithmic values - Log T ) and corresp ondent column emission measures EM logarithmic values. NOTE: if more than one value is entered, then the sequence must b e separated by commas (e.g.: 6.0, 6.5, 7.), and b oth Log T and Log EM must have the same numb er of values · - Photo excitation ? If set to yes, you have to define: Trad: The blackb o dy radiation field temp erature R/Ro: Distance from the centre of the star in stellar radius units · - Units: Photons or Ergs · - Protons: If set to Yes, the proton data are used to calculate the level p opulation Once all the parameters have b een defined, the user should click on the "Calculate intensities" button to start the calculation (which calls CH SYNTHETIC). Once the calculation is finished, an IDL structure is loaded into memory. It is then p ossible to save it for later use by clicking on the "SAVE" button. Once the IDL structure with the line intensities is in the memory, it is then p ossible to calculate and plot a sp ectrum (SECTION 2). 9.6.2 SECTION 2 - calculation of a synthetic sp ectrum

This section controls the parameters that are needed to fold the line intensities and the continua into a synthetic sp ectrum. These parameters are used by MAKE CHIANTI SPEC. Before this is done, a set of line intensities MUST b e in the program memory. This is done either by calculating the intensities or by restoring a save file with previously calculated values (SECTION 1). Setting the parameters: · -Minimum and maximum wavelengths. · -sp ectrum bin size in Angstroms in Angstroms. Disallowed if an Effective area file is used. · -instrumental FWHM: Setting this to a non-zero value broadens each of the sp ectral lines with a Gaussian of the sp ecified FWHM (in Angstroms) so mimicking the effects of instrumental broadening. · -continuum: Add continua to the binned sp ectrum: free-free, free-b ound and twophoton. Please note that the continuum calculation takes some time and you may want to define a minimum abundance value to sp eed the calculations. 43


· - All lines ? If set to no (default), only the lines for which there are observed energy levels are included. If set to yes, the "unobserved lines" will b e added, but only if they are present in the structure. · -elemental abundances: "*.abund" files (i.e. files with a .abund extension) can b e selected either from the CHIANTI database, the working directory, or via a widget. · -select a minimum abundance value: If set not null, only the lines of those elements which have an abundance greater than the value set are selected. Also, the continuum is calculated only for those elements which have an abundance greater than the value set. This can significantly sp eed up the calculations. By default, the minimum value in the selected abundance file is used. · Eff. Area: (Yes/No): If you want to fold the sp ectrum with an effective area. If set to Yes, you are requested to cho ose an input ascii file with two columns, the wavelength and the effective area values (cm2 ). The sp ectrum is multiplied with these values. the wavelenghts in the file (that might not b e linear) are used to create the sp ectrum. Note that this option only works well if a sufficient numb er of bins is given. The line intensities contributing to each bin are summed, and subsequently convolved with a gaussian of full-width-half-maximum FWHM, if FWHM is not set = 0. Please note that the convolution might not work if a small numb er of bins is defined. Also note that to have the correct output units (counts s-1 bin-1) the appropriately scaled DEM (or EM) values must b e provided. After this, by clicking on the "Calculate and plot" button the program calculates and plots the synthetic sp ectrum. Once the sp ectrum is displayed, it is then p ossible to view the details of the lines by clicking with the mouse in the plot window, and to p erform various op erations by clicking on the buttons in SECTION 3 9.6.3 SECTION 3 - selection of parameters for plotting and output

This Section allows the user to select a few parameters for the plotting, and to create different typ es of OUTPUT. · Lab els ? : Setting this to yes plots a vertical line for each sp ectral line in the sp ectrum, and also writes a lab el ab ove the strongest lines indicating the ion from which the line arises. · Min.: Only lines which have an intensity greater than the value set here will b e listed and, if requested, lab elled and selected for inclusion in the various outputs. Setting the value=0. will result in all lines b eing listed and written in the outputs. · X,Y, XOOM, UNZOOM: It si p ossible to select a region of the sp ectrum, by zo oming with the use of the mouse or by setting the X,Y ranges. NOTE that only the line details and p ortion of the sp ectrum shown will b e output. 44


· LINEAR/LOG To plot the sp ectrum in linear or log scale · Create PS file: A p ostscript file is created. · Hardcopy: the p ostscript file "idl.ps" is created and sent to the default printer. · Save Line details (latex): The details of the lines shown in the plot will b e saved in a latex file. · Save Line details (ascii): The details of the lines shown in the plot will b e saved in an ascii file. · Save Sp ectrum (ascii): The X,Y values of the sp ectrum are saved in an ascii file. · Save Sp ectrum (IDL/FITS): The details of all the lines and the arrays of the X,Y values of the sp ectrum are saved into an IDL or FITS file. Finally, SECTION 4 is a text information window, where various messages are printed. Clicking the cursor on any part of the displayed sp ectrum will give a listing of the lines within a range of Angtroms of that wavelength. Text information on the lines is printed.

9.7

Photo excitation from any user-provided radiation field

The radiation function used in Sect. 2.2 of the v.5 CHIANTI pap er for studying the O VI Doppler dimming problem is defined b elow. FUNCTION o6_lines, lambda, a ; ; ; ; ; ; ; Vernazza & Reeves (1978) give the quiet Sun O VI 1032 flux to be 305.28 erg/cm2/sr/s. The 1038 line is blended with C II, so I take it to be half of the 1032 line. I assume the FWHMs of the lines are 0.2 angstroms. A Velocity (km/s) relative to emitting ions of the structure emitting the radiation field. A positive velocity implies a redshift.

IF n_elements(a) EQ 0 THEN a=0. siz=size(lambda) spectrum=dblarr(siz[1],siz[2]) cc=2.998d5 p1=305.28/0.2 p2=p1/2. c1=1031.914 45 ; speed of light, km/s


c1=c1+ (a/cc * c1) ; c2=1037.615 c2=c2+ (a/cc * c2) w=0.2/2.35 i=where(abs(lambda-c1) LE 6.*w) IF i[0] NE -1 THEN spectrum[i]=p1*exp(-(lambda[i]-c1)^2/2./w^2)*4.*!pi/2.998d10 i=where(abs(lambda-c2) LE 6.*w) IF i[0] NE -1 THEN spectrum[i]=spectrum[i]+p2*exp(-(lambda[i]-c2)^2/2./w^2)*4.*! pi/2.998d10 return,spectrum END This function can then b e used in show p ops or emiss calc as follows: IDL> show_pops,8,6,radfunc='o6_lines, 20',rphot=1.1 where 'o6 lines, 20' indicates that the velo city A is set to 20 km/s. A zero velo city can b e set simply by using radfunc='o6 lines'. RPHOT sp ecifies the distance from the centre of the star in stellar radius units. The effects of many different velo cities can b e studied by doing, e.g., v=findgen(11)*10. for i=0,10 do begin radfunc_string='o6_lines, '+trim(v[i]) show_pops,8,6,radfunc=radfunc_string,rphot=1.1 endfor Up to 2 input parameters are allowed for radfunc and are sp ecified by, e.g., radfunc='radfunc, a, b'. Currently the RADFUNC= keyword is only available for the routines show p ops and emiss calc. Another example of radfunc is a blackb o dy function udens_bb, lambda t=6d3 ; temperature of Sun, 6000 K ee=1.439d8/lambda/t result=8.*!pi*1.986d-8/lambda^2*(1d8^3)/lambda^3/((exp(ee)-1)) return,result END 46


which is sp ecified to show p ops as IDL> show_pops,8,6,radfunc='udens_bb',rphot=1.1 The user should verify that this gives the same results as using the standard CHIANTI inputs IDL> show_pops,8,6,radtemp=6000.,rphot=1.1

9.8

Non-maxwellian distribution of electron velo cities

The following commands repro duce the numb ers in Table 3 of the v.5 CHIANTI pap er (Landi et al. 2005). Basically, we want to study the effects of non-Maxwellian distributions ° on two key line ratios of O VI, involving the strong lines at 1032 A, 173 ° and 150 ° We A A. consider a distribution comprised of two Maxwellians at log T = 5.5 and log T = 6.0, with the co efficients [a1,a2]=[0.75,0.25]. IDL> IDL> IDL> IDL> IDL> em=emiss_calc(8,6,temp=[5.5,6.0],sum_mwl_coeff=[0.75,0.25],dens=9.0) em150=em[40].em em173=em[43].em em1032=em[77].em print,em150/em1032,em173/em1032 0.030072876 0.043500302

The effects of non-Maxwellians on level p opulations can b e demonstrated with the show p ops routine, e.g., IDL> show_pops,8,6,lev=-8 Log10 density: Log10 temperature: 1 2 3 4 5 6 7 8 1s2.2s 1s2.2p 1s2.2p 1s2.3s 1s2.3p 1s2.3p 1s2.3d 1s2.3d 10.0 5.5 2S1/2 2P1/2 2P3/2 2S1/2 2P1/2 2P3/2 2D3/2 2D5/2 1.00e-00 2.30e-07 4.52e-07 5.07e-11 7.26e-12 1.44e-11 5.30e-12 7.96e-12

IDL> show_pops,8,6,lev=-8,temp=[5.5,6.0],sum_mwl_coeffs=[0.75,0.25] Log10 density: 10.0 47


Using a sum of Maxwellians 1 2 3 4 5 6 7 8 1s2.2s 1s2.2p 1s2.2p 1s2.3s 1s2.3p 1s2.3p 1s2.3d 1s2.3d 2S1/2 2P1/2 2P3/2 2S1/2 2P1/2 2P3/2 2D3/2 2D5/2 1.00e-00 2.26e-07 4.43e-07 8.93e-11 1.60e-11 3.16e-11 1.13e-11 1.69e-11

where it can b e seen that the n=3 level p opulations are enhanced by factors 2 by the high temp erature comp onent to the distribution.

9.9

Lo oking at level p opulations

To plot the p opulations of the first 4 levels of Si I I I as a function of density at a temp erature of 3 x 104 K: IDL > plot_populations,'si_3',3.e+4,4

Figure 5: Output plot of PLOT POPULATIONS Optionally, output files can b e created. Alternatively, SHOW POPS can b e used. This routine has a large range of features implemented via keywords.

48


9.10

Lo oking at the pro cesses that p opulate each level

To assess the contributions of the different physical pro cesses to the p opulation of a sp ecified level within an ion, use POP PROCESSES. IDL> pop_processes,'fe_13',lev=4 Level: 3s2.3p2 1D2 6.2 10.0 level 4 1.60e+01 3.29e-01 2.10e+01 2.44e-01 3.75e-02 0.00e+00 0.00e+00 -------3.77e+01

Log10 Temperature: Log10 Density: Population leaving rad. decay: e de-exc: e exc: p de-exc: p exc: stim. emiss: photoexc: TOTAL

42.50% 0.87% 55.88% 0.65% 0.10% 0.00% 0.00%

Population entering level 4 rad. decay: 3.50e+01 e de-exc: 3.38e-02 e exc: 1.47e+00 p de-exc: 2.81e-03 p exc: 1.13e+00 stim. emiss: 0.00e+00 photoexc: 0.00e+00 -------TOTAL 3.77e+01

92.98% 0.09% 3.92% 0.01% 3.01% 0.00% 0.00%

which shows that the level p opulation is dominated by electron excitation and cascading into the level, and by radiative decay out of the level. Note that the rates for each physical pro cess are multiplied by the p opulation of originating level (this results in the totals for entering and leaving the level to balance).

9.11

Searching for a line

If you want to list the lines within one ion around some wavelengths, you can use WHICH LINE. For example, 49


IDL> which_line,'o_6',1032 Wavelength 1031.914 1037.615 i 1 1 j 3 2 Lower level 1s2.2s 2S1/2 1s2.2s 2S1/2 Upper level - 1s2.2p 2P3/2 - 1s2.2p 2P1/2 A-value 4.28e+08 4.21e+08

*

Prints a list of atomic transitions and wavelengths for lines from O VI within 1% of the input wavelength (1032 ° A).

9.12

Lo oking at the different ionisation equilibria

If you are interested to see the differences b etween the various ionisation equilibria for e.g. Mg, you can use: IDL > plot_ioneq,'Mg' You will b e able to select one of the files, and optionally create a p ostscript file of the plot.

Figure 6: Output plot of PLOT IONEQ If you are only interested in e.g. the Mg VI I I, Mg IX, Mg X ions, you can typ e: IDL > plot_ioneq,'Mg', ion=[8,10]

50


If, instead, you are interested in obtaining the temp erature at the maximum ionisation fraction for e.g. Mg X, you can use: IDL > print, max_temp ('Mg X') You will b e asked to select an ionisation equilibrium file.

9.13

Density and temp erature diagnostics from line ratios

Sp ectroscopic diagnostic line ratios in the UV wavelength range have b een used extensively to determine the electron density and temp erature in the solar atmosphere (cf Dere and Mason, 1981, Gabriel and Mason, 1982, Mason, 1991, Mason and Monsignori Fossi, 1994). The theoretical intensity ratios from individual ion sp ecies provide a measurement of electron density which is indep endent of any assumptions ab out the volume of the emitting region. This is of particular imp ortance in the transition region and coronal structures. The electron density (which determines the electron pressure) is an essential parameter in the study of energy transfer mechanisms. The routines that can b e used are describ ed b elow. 9.13.1 The DENS PLOTTER and TEMP PLOTTER widgets

DENS PLOTTER and TEMP PLOTTER are high-level widgets for the analysis of densityand temp erature-sensitive ratios of lines from the same ion. They allow inclusion of proton rates and photo excitation. The calling sequence is simple: IDL > dens_plotter,'o_5' to study O V. IDL > temp_plotter,'c_4' to study C IV. Alternatively, you can use the command-line routines, DENSITY RATIOS and TEMPERATURE RATIOS. They also allow inclusion of proton rates and photo excitation via KEYWORDS. 9.13.2 The DENSITY RATIOS pro cedure

The routine DENSITY RATIOS plots the variation of line intensities with electron density, allowing density diagnostics to b e studied. As an example, we can lo ok for density sensitive line ratios of O V in the 1000 to 1500 ° wavelength region for densities b etween 108 and A 1013 cm-3 : IDL > density_ratios,'o_5',1000.,1500.,8.,13.,den,rat,desc

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two windows will op en and plot the relative intensities of a few O V lines. To cho ose the ratio of 1371.294 to 1218.393 ° line, select first the 1371.294 ° line. Another widget will A A ° line. This will chose the ratio of app ear to select the denominator. Select the 1218.393 A 1371.294 to 1218.393 which will b e plotted in a new window. Values of the density and intensity ratio will b e put into the variables den and rat and desc will contain a descriptive string. IDL > print, desc IDL > CHIANTI V. 4.0 O V 1371.2939 ()/1218.3929 ()

T = 2.51e+05 (K)

The DENSITY RATIOS pro cedure also allows to calculate the ratio at user-defined value of constant temp erature. Blends are accounted for via a selection of lines. 9.13.3 The TEMPERATURE RATIOS pro cedure

To calculate temp erature sensitive line ratios of C IV for lines b etween 100 and 1600 ° for A 4 6 temp eratures b etween 10 and 10 K: IDL > temperature_ratios,'c_4',100.,1600.,4.,6.,temp,rat,desc

As with density ratios, a widget will app ear that will allow you to select the numerator. Select the 384.175 and 384.190 ° lines as these will typically b e blended in most sp ectrographs. A ° line for the denominator. The ratio of (384.175 + 384.190 ° to the Select the 1550.775 A A) 1550.775 ° line as a function of temp erature will b e plotted and stored in the variables rat A and temp, resp ectively. The TEMPERATURE RATIOS pro cedure also allows to calculate the ratio at user-defined values of either constant pressure or constant density. IDL > print, desc IDL > CHIANTI V. 4.0 C IV 384.1750+384.1900 ()/1550.7750 () Ne = 1.00e+10 (cm!e-3!n) 9.13.4 The CHIANTI NE and CHIANTI TE widgets

The IDL pro cedure which calculates line intensity ratios as a function of electron density is called CHIANTI NE. Another IDL pro cedure to calculate ratios sensitive to electron temp erature is called CHIANTI TE. For example, IDL > chianti_te Or IDL > chianti_ne User interactions with the main widget setup the wavelength range and other parameters that are describ ed individually b elow. On the left hand side are controls for wavelength and electron density or temp erature selection and on the right hand side for ion selection. Ion selection 52


Select first the element and then the ion stage using the pull-down menus. Only those elements and ions currently available in the CHIANTI database are displayed for selection. Wavelength ranges There are up to 4 wavelength ranges that can b e defined in order to restrict the calculation (and the numb er of lines). At least one should b e defined. Default is to calculate all lines from 1 to 1700 ° A. Electron Density/Temp erature Range For CHIANTI NE, select the electron numb er density range (Log10 Ne ) over which the intensity ratios are calculated. Default values are 106 to 1014 cm-3 . The intensity ratios are calculated at constant temp erature corresp onding to the p eak ionic abundance Tmax , unless the value of the temp erature is typ ed in. For CHIANTI TE, select the electron temp erature (Log10 Te ) over which the intensity ratios are calculated. Default values are 104 to 108 K. The intensity ratios are calculated at a constant electron numb er density corresp onding to 108 cm-3 , unless a different value is typ ed in. minimum intensity ratio The relative intensity of all the lines found in the wavelength range is calculated. Only the lines that have an intensity (relative to the brighter one) greater than 0.0001 (by default) are selected and displayed. Units for the ratio plot The ratios can either b e calulated from the relative intensities in ergs (default) or photons. Controlling the pro cedure The action of b oth CHIANTI NE and CHIANTI TE is controlled via the buttons in the central panel of the display. From left to right these are: QUIT - click on this to exit from the program, all plot windows are also deleted. CALCULATE LINE INTENSITIES - using the wavelength ranges as defined in the widgets ab ove. Two plots will ap ear in the window - on the left the Ni A/Ne and on the right the intensity ratios, where Ni is the level p opulation and A is the radiative transition probability (s-1 ). A list of sp ectral lines in the given wavelength range for that ion is displayed in the message window. The reference index is in the first column, then the wavelength, intensity and transition. PLOT RATIO - prompts for and then plots sp ecific line intensity ratios, using line indices available from the list. The ratios within a particular ion can b e stored for later use using the SAVE button. To allow for blended lines in the observed sp ectra, multiple line indices can b e given for the numerator and denominator. The format is fairly flexible but the nominator and denominator sp ecification must b e separated by a '/'. Otherwise the line indices can b e separated by spaces or commas. The ratio values can b e plotted either with a linear or a log scale. HARDCOPY - the menu under this button will allow a variety of hardcopy plots (ratio plots or intensity plots) and the line details (+refs), which gives a record of the input. A line ratio has to b e defined. SAVE - it is sometimes useful to save the plotted line intensity ratios to study several different ions. You will b e asked to enter file name to store ratio data. A line ratio has to b e defined. In the CHIANTI NE case, a .CH NE will b e app ended. An IDL structure called NE RATIO will b e saved. It has the TAGS: DENSITY,RATIO, TEMPERATURE, UNITS, COM53


MENT, DESC. The first two have the arrays of the densities and ratios, TEMPERATURE has the value of the constant temp erature used, while the last three have a description of the units used, how the calculation was p erformed, and a description of the lines used to defined the ratio. In the CHIANTI TE case, a .CH TE will b e app ended. An IDL structure called TE RATIO will b e saved. It has the TAGS: TEMP, RATIO, DENSITY, UNITS, COMMENT, DESC. The first two have the arrays of the temp eratures and ratios, DENSITY has the value of the constant density used, while the last three have a description of the units used, how the calculation was p erformed, and a description of the lines used to defined the ratio. Please note that previous versions of the ab ove routines did not create the TEMPERATURE (DENSITY), UNITS, COMMENT tags. The save file can b e restored and replotted outside of CHIANTI NE and CHIANTI TE using the pro cedures PLOT CHIANTI NE and PLOT CHIANTI TE resp ectively, or used within user-defined pro cedures. DELETE PLOT WINDOWS - to clear the ratio plots from the screen. 9.13.5 The PLOT CHIANTI NE and PLOT CHIANTI TE pro cedures

The ratio values stored in the save files created with the CHIANTI NE and CHIANTI TE routines can b e replotted outside of CHIANTI NE and CHIANTI TE using the pro cedures PLOT CHIANTI NE and PLOT CHIANTI TE resp ectively. For example, IDL > plot_chianti_te Or IDL > plot_chianti_ne If no files are sp ecified, a widget allows you to select any '*.CH NE' or '*.CH TE' files. A LOG keyword allows the user to have the plot in a log scale. It is also now p ossible to interactively mo dify the X and Y ranges and to create a p ostscript file. Users can mo dify these routines to e.g. over-plot observed data p oints. 9.13.6 Calculating temp eratures by using different ions

Note: If you are interested in determining an isothermal temp erature by using the ratio of lines emitted by different ions (and/or elements), then a p ossible way is to first calculte the contribution functions of the lines you are interested, and then calculate their ratio. Note, however, that such determinations can b e very inaccurate, since they dep end on the ionisation equilibrium chosen (and eventually on the element abundance).

9.14

Calculating contribution functions

To calculate the contribution function ( er g cm3 s-1 sr -1 by default) vs. temp erature at a sp ecified abundance, ionization equilibrium and pressure or density for the Fe XXIV line at 255.1 ° A: 54


IDL >

gofnt,'fe_10',170.,180.,temperature,g,desc

temp erature, g are the arrays with the temp eratures and the G(T) values. It is p ossible to calculate the G(T) at either constant electron density or pressure, via the KEYWORDS DENSITY or PRESSURE. The KEYWORDS ABUND NAME, IONEQ NAME allow to run the routine in the background, giving names of the abundance and ionization fractions files. The routine GOFNT allows the user to select a numb er of lines. If this is done, then the total sum of the G(T)'s of the selected lines is returned and plotted. Optional outputs can b e created. The default units are er g cm3 s-1 sr -1 , unless the KEYWORD /PHOTONS is set, in which case the units are photons cm3 s-1 sr -1 .

9.15

Calculating radiative losses

A pro cedure ('RAD LOSS') calculates the total radiative loss rate as a function of temp erature for sp ecified set of abundances and/or ionization equilibria: IDL > rad_loss,temperature,loss_rate

Figure 7: Output plot of RAD LOSS

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9.16

The calculation of the DEM

Given a set of observed sp ectral intensities, the problem is to invert a system of integral equations like the previous one. The pro cedure CHIANTI DEM solves the system and calculates the D E M (T ). The inversion problem itself is not simple and requires some assumptions ab out the nature of the solution. A series of workshops was sp onsored in 1990/91 to study differential emission measure techniques (Harrison and Thompson, 1992). It was found that most co des eventually gave consistent results, but that the DEM derived dep ends rather critically on the metho ds used to constrain the solution and the errors in the observed intensities and atomic data. It is advisable to select a numb er of well resolved, unblended lines which are not density sensitive, emitted by various elements over a wide temp erature interval. Appropriate values of the pressure (or density) and the elemental abundances must b e chosen according to the region of the Sun b eing observed. The pressure value can b e obtained once the values of the temp erature and the density are estimated. To estimate the electron density the pro cedure CHIANTI NE can b e used. The temp erature can b e estimated for example using the pro cedure CHIANTI TE. The contribution functions C (T , ij , Ne ) can b e calculated using CHIANTI DEM either at constant pressure or at constant electron density. It is also p ossible to vary the elemental abundances b efore starting the fit to deduce the DEM. Many pap ers have b een written on solar elemental abundances. See e.g. Meyer (1993) Widing and Feldman (1992), Mason (1992, 1995). A p ossible approach in determining elemental abundances is to use the detailed shap e of the DEM distribution for ions from the same element and apply an iterative pro cedure to normalize the curves for different elements (e.g. Fludra and Shmelz 1995, Del Zanna et al. 1995). The CHIANTI DEM pro cedure The main IDL routine which has b een written to p erform a differential emission measure analysis of EUV sp ectra using the CHIANTI atomic database is CHIANTI DEM. Other pro cedures required to run CHIANTI DEM are GET CONTRIBUTIONS , DEM FIT, ZION2SPECTROSCOPIC and Z2ELEMENT. The resulting DEM may then b e used by other pro cedures to calculate a synthetic sp ectrum. This package of routines will b e replaced in the future by new more versatile versions. The main inputs required by CHIANTI DEM are : · the file with the observed fluxes. It can b e selected using a widget-typ e browse from within CHIANTI DEM or using the optional keyword FILE INPUT='myfilename' . It must contain 5 columns of unformatted data ( separated by at least one space). The 5 fields are: 1) the observed wavelength obs [° A]. 2) The observed flux I
obs

in er g s cm-2 s-1 sr -1 .

3) The corresp onding error obs on the flux in er g s cm-2 s-1 sr -1 . 4) The value of [° All the theoretical lines that may have contributed to the A]. observed lines, i.e. that have a theoretical wavelength theo in a obs ± range will b e

56


searched for. This value should corresp ond to the sp ectral resolution of the instrument at that wavelength. 5) The identification, written as a string of up to 20 characters. For example: 171.114 4811.0 1443.0 0.25 Fe IX 174.604 4005.0 1202.0 0.25 Fe X 180.448 3877.0 1163.0 0.25 Fe XI bl Fe X 195.149 3443.0 1033.0 0.25 Fe XI I · the pressure Ne T [cm-3 K ] or the density Ne [cm-3 ], passed to the routine via a keyword. · the ionization equilibrium file, selected using a widget. · the elemental abundances file. A selection of files are already stored in the CHIANTI package, but user-defined files in the working directory can also b e used. Any *.abund file present in the CHIANTI database or in the working directory can b e selected through a widget from within CHIANTI DEM. The selected file can also b e edited. · An output file name must also b e supplied via a keyword (e.g. OUTPUT= 'active region'). Various files will b e generated by CHIANTI DEM having file names created by adding suffixes to the output file name. Once the file with the observed fluxes is read, another IDL pro cedure, GET CONTRIBUTIONS, is called by CHIANTI DEM in order to calculate the contribution functions C (T , ij , Ne ) at the given constant density or pressure. GET CONTRIBUTIONS searches the CHIANTI database for all the theoretical lines that may have contributed to the observed lines, i.e. that have a theoretical wavelength theo in a obs ± interval. Then, for each theoretical line selected, it calculates the C values for the temp erature interval log(T)= 4.0 - 8.0 in steps of log(T) = 0.1. If a constant pressure is selected, for each ion the contribution function is calculated at an electron density Ne equal to the ratio of the pressure and the temp erature of maximum ionization fraction. The C (T ) values are stored by GET CONTRIBUTIONS in the output file output.contributions that can b e used later, if required, to re-calculate the DEM, changing various parameters (e.g. the abundances), without having to start again and read the CHIANTI database, which can take a long time. The observed lines with no theoretical counterparts are automatically excluded. If this happ ens, you might consider starting again with a larger , to see if there are theoretical lines in the vicinity of the observed one. Then you are asked to select an *.abund file present in the CHIANTI database or in the working directory, and eventually edit it, if you want to change some abundances. The G(T ) are calculated, multiplying each theoretical line by the abundance factor. The theoretical lines contributing to each blend are sorted by intensity and then their G(T) can 57


b e plotted if the keyword PLOT GT was activated. It is recommended to do this the first time, to check if there are some observed lines which are heavily blended with lines of other elements. It might b e b etter to exclude such lines in a second run. The G(T ) for each blend are then summed and plotted, and the calculation of the DEM starts, using the fitting routine DEM FIT. A series of parameters can change the result (DEM), esp ecially the numb er and p osition of the mesh p oints of the spline that represents the DEM. The fitting pro cedure is based on Bevington's Data Reduction and Error Analysis for the Physical Sciences. fortran programs. The iteration is controlled using key-words (see b elow). A series of outputs are created, all having extensions of the output name. For example, using test as the output name: · test.contributions: The first three lines contain the abundance file, the ionization equilibrium file names, and the constant value of the pressure or the density adopted. Each subsequent line contains the observed wavelength obs , the theoretical one theo , the element and ionization stage, the C (T ) values and the sp ecification of the transition. · test.dem: Is the file where the D E M (T ) values are written, in a format suitable for input to the CHIANTI SS pro cedure which may b e used to calculate a synthetic sp ectrum from the DEM. · test.general: Is the file where general information is stored. The abundance file, the ionization equilibrium file and the pressure used are written at the b eginning. Then there is one line for each observed line, with the identification present in the input file, the observed wavelength obs , the observed flux Iobs , the calculated flux Itheo - , the error on the flux obs , the value ( ItheoobsIobs )2 and finally the value of IItheo obs After this line, there is one line for each theoretical line contributing to the blend, with the identification, the theoretical wavelength theo , the configuration and terms, and the contribution (as a p ercentage) of each line in the blend to Itheo . · test.out: This file , toghether with test.dem, can b e used to repro duce the results using user-written software. It contains: the identification present in the input file, the observed wavelength obs , the observed flux Iobs , the calculated one Itheo , the error on the flux obs , and the logarithmic values of the temp erature and the DEM for each observed line. This temp erature is the value where the pro duct G(T ) D E M (T ) has a maximum. · three optional p ostscript files: test gt.ps test dem.ps test 4plots.ps . The first one has the G(T ) of all the lines then used for the fit, with all the contributions for each line summed ( the lab els refer to the identifiacation given in the input file). The file test dem.ps has the D E M (T ) with the scales set as in the interactive session. The p oints are plotted at the temp erature where the pro duct G(T)*DEM(T) has a maximum. It is p ossible to lab el the p oints with the comment string present in the input file, or to use the dominant ion in the blend. 58


The file test 4plots.ps has some additional plots. The upp er-right figure of test 4plots.ps plots the values IItheo versus the temp erature where G(T) has it's maximum. obs · It is also p ossible to have p ostscript files of the G(T) functions, using the keyword PLOT GT. 9.16.1 Controlling the pro cedure

The action of CHIANTI DEM is controlled via the following keywords. · FILE INPUT: optional; if not set, you are prompted to select the observation file using a widget-typ e search. · ARCSEC: optional set this if the intensities are sp ecified in units p er arcsec-2 . The default units are er g s cm-2 s-1 sr -1 . · PHOT: optional; set this if the intensities are sp ecified in units p er steradians-1 . The default units are er g s cm-2 s-1 sr -1 . · OUTPUT : required; the name for the output. Suffixes will b e added to this name when creating the various outputs. · FILE GT: if not set, the routine GET CONTRIBUTIONS is called. Either the pressure or the density must b e set in this case. If set, it has to sp ecify the name of the file previously created by GET CONTRIBUTIONS, where all the contribution functions C (T ) are stored. · PRESSURE: the value of the pressure (Ne T). Required if you do not already have the contribution functions C(T) (i.e. if you do not set FILE GT). Either the pressure or the density must b e set in this case. · DENSITY : the value of the electron density (Ne). Required if you do NOT already have the contribution functions C(T). Either the pressure or the density must b e set in this case. · CUT GT: optional; if set, only those theoretical lines that have a M AX (C (T )) greater than the value set, are kept; it is useful to set this value in order to reduce the numb er of lines in the file where the C (T ) are stored. If not set, a default value of 10-30 is adopted. · N MATCHES: optional; in the unlikely event that more than 20 (default value for N MATCHES) theoretical lines corresp onding to an observed line are found, the routine stops. In this case, you have to start again setting N MATCHES equal to a greater numb er. · PLOT GT: optional; if set, plots of the G(T ) of the theoretical lines contributing to each observed line not excluded are created. It is p ossible to change the scale and create p ostscript files of these plots, interactively. 59


· EXCLUDE OBS WVL: optional; if set, has to b e an array that sp ecifies the wavelengths of the lines that you want to exclude from the fit. Note that even if you set this keyword and run GET CONTRIBUTIONS all the theoretical lines found corresp onding to all the lines in the input file are written in the C (T ) file. It is only in the fit that the lines are excluded. · MESH POINTS: optional; it is an array that sp ecifies the mesh p oints for the spline that represent the fitted DEM, in log(T). If not set, the default values [4,4.5,5,5.5,6,6.5,7,7.5,8] are assumed. · N ITER: optional; it is the maximum numb er of iterations of the fitting routine. If not set, a default value of 20 is assumed. Changing this value alone might not affect the fit, since the value of DCHISQ M is monitored at each iteration to check for convergence. · DCHISQ M: optional; if not set, a default value of DCHISQ M= 1 · 10-5 is assumed. For each iteration, the 2 and it's variation are calculated. As long as the iteration achieves a relative improvement in 2 greater than DCHISQ M , another iteration will b e p erformed. · DEM FILE: optional; if set you are prompted to cho ose a DEM file to b e used initially, instead of the default constant value of 1022 . You can either cho ose one of the files in the CHIANTI database or any you have in the working directory. A plot of the DEM is created. The values in the file are marked as crosses, the mesh p oints are marked with triangles. · QUIET: optional. Set to avoid various messages and the details of the result. There are also some actions When you are asked for an The capital letter in [y/N] simply hit the return key. cho osing y . 9.16.2 Examples controlled via the keyb oard. answer ( [y/N] ) yes or no you should either typ e in y or n. means that the default choice is n which is what you get if you In case you have [Y/n], hitting the return key is the same as

You must sp ecify the output file name and the value of the pressure (or the density). The input file name is optional. IDL > CHIANTI_DEM,OUTPUT='test',FILE_INPUT='test_obs',PRESSURE=1e16,/PLOT_GT Select the ionization equilibrium file (e.g. Arnaud & Raymond). If there are no problems ab out N MATCHES, the routine will select the lines having max(C (T )) 10-30 and write the C (T ) values to the file test.contributions. Then you'll b e asked to select an abundance file and if you want to edit it. Pick up the Feldman abundances. Then the G(T ) are calculated, multiplying each theoretical line by the abundance factor, sorted (within each blend) by their max(G(T )) value, and plotted ( see Fig. 8). 60


Figure 8: One of the G(T) plot of the test case It is recommended that you check the plots at least once, to see if there are some observed lines that it might b e b etter to exclude in a second run, for example b ecause they are blends. Also check if your identifications are consistent with the lines found in the CHIANTI database. The G(T) for each blend are then summed, and plotted ( see Fig. 9). At the end of the fit, the files test.dem, test.general, test.out are created. Have a close lo ok at these outputs, and check if there are emission lines not well represented by the fit or with no theoretical counterparts. You can use the routine a second time, excluding some of the lines, and/or varying some of the fitting parameters. In particular, changing MESH POINTS or starting from an appropiate DEM can affect the resulting DEM. For example: IDL> CHIANTI_DEM,OUT='test',FILE_IN='test_obs',FILE_GT='test.contributions', $ IDL> EXCLUDE_OBS_WVL=[ 284.153 ] ,$ IDL > MESH_POINTS= [ 4.85, 5.6, 6.25, 7.0 ],N_ITER=40 The files test.dem, test.general, test.out will b e created. Eventually, also the files test dem.ps test 4plots.ps may b e created. Fig. 10 shows the resulting DEM. The error bars on the p oints simply repro duce the error on the observed fluxes. The Fig. 11 is self-explanatory. The DEM figure is rep eated in the upp er-left plot with the same scale of the previous plot. 61


Figure 9: The summed-G(T) plot of the test case: test gt.ps

Figure 10: The DEM plot of the test case: test dem.ps 62


Figure 11: The 4 plots of the test case: test 4plots.ps The file test.out , toghether with test.dem, can b e used to repro duce these plots using userwritten software. If the only concern is the p ostscript output, then users just have to copy the routine in the working area and mo dify the top pro cedure PRINT2D PLOT.PRO that controls the p ostscript device. The default is landscap e. 9.16.3 Some final remarks

This package is mostly intended to b e a quick metho d to obtain a DEM which can then b e used to calculate a synthetic sp ectrum, to b e compared with the observed data. Try to give as input lines covering a broad range in temp eratures, and that are not density sensitive. Try to adjust the lo cation of the mesh p oints. If the resulting DEM do es not give a go o d fit to the data, it might b e a go o d idea to start again calculating the G(T ) with different abundances or to check the effect of blends. Try a different DEM as a starting p oint, but b e careful ab out the end p oints at lower and higher temp eratures where usually there are no constraints (no observed lines). Consider the p ossible effect on the DEM of different structures along the line of sight. It is imp ortant to realise that the DEM gives an indication of the amount of plasma at different temp eratures along the line of sight, assuming constant density or pressure. It is not therefore p ossible to infer direct information ab out the variation of the temp erature with height from this function. The inclusion of density-sensitive lines in the fit may also cause problems. Send comments to : Giulio Del Zanna g.del-zanna@damtp.cam.ac.uk 63


References
[1] Jordan, C. & Wilson, R. (1971). In: Physics of the Solar Corona, (ed. C. J. Macris), p. 199, Reidel, Dordrecht [2] Jordan, C. & Brown, A. (1981). In: Solar Phenomena in Stars and Stel lar Systems, (eds. R. M. Bonnet and A. K. Dupree), p. 199, Reidel, Dordrecht [3] Pottasch, S. R. (1964). Space Sci. Rev. 3, 816 [4] Thomas, R. J. & Neup ert, W. M. (1994). ApJS 91, 461 [5] Young, P. R., Landi, E., & Thomas, R. J. (1998). AA 329, 291 [6] Allen, C.W., 1973, Astrophysical Quantities. [7] Arnaud, M. & Raymond, J.C. 1992, Astrophys. J., 398, 39. [8] Arnaud, M. & Rothenflug, R. 1985, Astro. Astrophys. Suppl. Ser., 60, 425. [9] Bely-Dubau, F., 1995, Adv. Sp. Res., 15. [10] Brickhouse, N.S., Edgar, R., Kaastra, J., Kallman, T., Liedahl, D., Masai, K., Monsignori Fossi, B., Petre, R., Sanders, W., Savin, D.W. & Stern, R. 1995, Napa Val ley Meeting, November 1994 [11] Burgess, A. and Tully, J.A., 1992, Astron. Astrophys., 254, 436. [12] Dere, 1978, A&A, 70, 439 [13] Dere, K.P. and Mason, H.E., 1981, Active Regions, Ch. 6, ed. F.Orrall, (Publ. C.U.P.). [14] Dere, K.P. and Mason, H.E. 1993, Sol. Phys., 144, 217. [15] Dere, K.P., Landi, E., Young P.R., Del Zanna, G., 2000, submitted to Astrophys. J. Suppl. Ser. [16] Del Zanna, G., Landini, M. and Mason, H.E., 2002, A&A 385, 968. [17] Fludra A., Schmelz J.T.: 1995, Astrophys. J., 447, 936 [18] Gabriel, A.H. and Mason, H.E., 1982, Applied Atomic Col lision Physics, Ch. 12, Solar Physics, eds. H.S.W. Massey, B. Benderson, E.W. McDaniel, (Publ. Academic Press). [19] Grevesse, N., and Anders, E., 1991, in Solar Interior and Atmosphere, eds. A.N. Cox, W.C. Livingston, and M.S. Matthews, (Tucson: Univ. Arizona Press), 1227 [20] Harrison, R.A. & Thompson, A.M., 1992, RAL-91-092. [21] Itikawa, Y. , 1991, A.D.N.D.T., 49, 392. [22] Itoh, N., Sakamoto, T., & Kusano, S., 2000, APJS, 128, 125 64


[23] Jordan, C. 1995, Astron. Soc. of the Pacific, in press. [24] Karzas and Latter (1961) [25] Landi, E., Landini, M., Dere, K. P., Young, P. R., and Mason, H. E., 1999, A&AS, 135, 339 [26] Landini, M., Monsignori Fossi, B. C., 1991, A&AS, 91, 183 [27] Lang,J., 1994, A.D.N.D.T., 57. [28] Mason, H.E., 1991, Adv. Sp. Res., 11, (1) 293. [29] Mason, H.E., 1992, Proc. of the First SOHO Workshop, Annapolis, Maryland, 25-28 Aug. '92, ESA SP-348, 297. [30] Mason, H.E. and Monsignori Fossi, B.C., 1994, The Astron. Astrophys. Rev., 6, 123. [31] Mason, H.E.: 1995, Adv. Space Res., 15, 53. [32] Mazzotta, P., Mazzitelli, G., Colafrancesco, S., & Vittorio, N. 1998, A&AS, 133, 403 [33] Mewe, R. 1972, Sol. Phys., 22, 459. [34] Meyer, J.-P., 1985, Astrophys. J. Suppl. Ser., 57, 173. [35] Meyer, J.-P., 1993, Adv. Space Res., 13(9), 377. [36] Monsignori Fossi, B.C. and Landini, 1994, Sol. Phys., 152, 81. [37] Monsignori Fossi, B.C., Landini, M. Thomas, R.J. and Neup ert, W.M., 1994, Adv. Space Res., 14, (4) 163. [38] Monsignori Fossi, B.C. and Landini, M., 1995, I.A.U Col loquium No 152, Astrophysics in the EUV, Berkeley, March 1995, ed. S. Bowyer, in press. [39] Pottasch, S.R., 1964, Sp. Sci. Rev., 3, 816. [40] Pradhan, A.K., and Gallagher, J.W., 1992, A.D.N.D.T., 52, 227. [41] Raymond, J. C. et al., 2001, in Solar and Galactic Comp osition, AIP Conf. Pro c., 598, 49 [42] Sutherland, R. S., 1998, MNRAS, 300, 321. [43] Waljeski, K., Moses, D., Dere, K.P., Saba, J.L., Strong, K.T., Webb, D. F., and Zarro, D.M., 1994, Astrophys. J., 429, 909. [44] Widing, K.G. & Feldman, U., 1992, Proc of the Solar Wind Seven Conference, Goslar, Germany, 16-20 Sept. 1991, eds. E. Marsch, R.Schwenn, 405. [45] Young, P. R., Landi, E., Thomas, R. J., 1998, A&A, 329, 291 65


[46] Young, P. R., Del Zanna, G., Landi, E., Dere, K.P., Mason, H.E., and Landini, M., 2002, ApJ, submitted.

66


A
A.1
·

Description of the CHIANTI V.4 software updates
Routines already available in Version 3
ascii_wvl_dem.pro creates an ascii file with a list of line identifications and intensities. Compared to the previous version, these are the main changes: 1-Rewritten as a wrapp er routine using the new pro cedures. 2-Now the PRESSURE value is a keyword. 3-The calculations can b e done at constant DENSITY. 4-Energies (keV) can b e output instead of wavelengths in Angstroms 5-MASTERLIST can now b e used b oth as an input string or as a keyword. · latex_wvl_dem.pro creates a latex file with a list of line identifications and intensities. Compared to the previous version, these are the main changes: 1-Rewritten as a wrapp er routine using the new pro cedures. 2-Now the PRESSURE value is a keyword. 3-The calculations can b e done at constant DENSITY. 4-MASTERLIST can now b e used b oth as an input string or as a keyword. · synthetic.pro Calculates a synthetic sp ectrum. It outputs arrays. Compared to the previous SYNTHETIC, these are the main changes: 1-Rewritten as a wrapp er routine using the new pro cedures. 2-Now the PRESSURE value is a keyword as the DENSITY value 3-The keyword CONT is now renamed CONTINUUM 4-Added keywords PHOTONS (If set, intensities are in photons instead of ergs) to run the routine in the background, giving names of the DEM, abundance and ionization fractions files.

The previous routines have b een mo dified as describ ed:

DEM_NAME, ABUND_NAME, IONEQ_NAME,

NOPROT (If set, then proton rates are not included.) RADTEMP, RPHOT (to include photoexcitation)

67


5-MASTERLIST can now b e used b oth as an input string or as a keyword. 6-The description of the line details now has the sp ectroscopic designation at the end. · synthetic_plot.pro plots the sp ectrum and interactively identify lines Is left unchanged except for a few minor changes. · gofnt.pro calculates the contribution functions Aside from a few small fixes, these are the main changes: 1-Rewritten as a wrapp er routine using the new pro cedures. 2-Added keywords

ABUND_NAME, IONEQ_NAME,

to run the routine in the background, giving names of the abundance and ionization fractions files.

NOPROT (If set, then proton rates are not included.) RADTEMP, RPHOT (to include photoexcitation)

· isothermal.pro Calculates line intensities with an isothermal approximation. Compared to the previous routine, these are the main changes: 1-Rewritten as a wrapp er routine using the new pro cedures. 2-Added keywords

ABUND_NAME, IONEQ_NAME,

to run the routine in the background, giving names of the abundance and ionization fractions files.

NOPROT (If set, then proton rates are not included.) RADTEMP, RPHOT (to include photoexcitation) EM Emission measure values.

· chianti_ss.pro Widget for creation of SOHO synthetic sp ectra. Is not distributed nor supp orted anymore. Is now replaced by ch_ss.pro 68


· plot_populations plots the level p opulations Compared to the previous routine, these are the main changes: 1-Mo dified the plotting, adding information ab out the single lines. 2-Added keywords

NOPROT (If set, then proton rates are not included.) RADTEMP, RPHOT (to include photoexcitation)

·

density_ratios plots the variation of line intensities with electron density Compared to the previous routine, these are the main changes: 1-Rewritten as a wrapp er. 2-Added keywords

NOPROT (If set, then proton rates are not included.) RADTEMP, RPHOT (to include photoexcitation)

·

temperature_ratios plots the variation of line intensities with electron temp erature 2-Added keywords

PHOTONS

(If set, intensities are in photons instead of ergs)

IONEQ_NAME The ionization fractions file. NOPROT (If set, then proton rates are not included.) RADTEMP, RPHOT (to include photoexcitation)

·

freefree calculates the free-free (bremsstrahlung) continuum The call is the same, but the calculations are done using the fitting formulae of Itoh et al. (ApJS 128, 125, 2000) and Sutherland (MNRAS 300, 321, 1998). Also, a few bugs have b een fixed.

69


· freebound.pro calculates the free-b ound continuum Added the keyword PHOTONS (If set, intensities are in photons instead of ergs) · rad_loss.pro calculates the radiative losses -Added keywords

NOPROT (If set, then proton rates are not included.) RADTEMP, RPHOT (to include photoexcitation)

A.2

Other routines that were previously available only within SolarSoft

These routines are in the other/ sub directory: · max_temp.pro Calculates temp erature at max ionisation ratio for an ion Unchanged. · plot_ioneq.pro Plots the ionisation equilibrium values for an element. Unchanged. · chianti_ne.pro Calculate and plot density sensitive line ratios. Widget unchanged but the low-level routine now uses emiss_calc.pro. · plot_chianti_ne.pro Plots a density sensitive ratio saved from CHIANTI_NE Unchanged. · chianti_te.pro Calculate and plot temp erature sensitive line ratios. Widget unchanged but the low-level routine now uses emiss_calc.pro. · plot_chianti_te.pro Plots a temp erature sensitive ratio saved from CHIANTI_TE Unchanged. · chianti_dem.pro Calculates the Differential Emission Measure DEM(T) using the CHIANTI database, from a given set of observed lines. Changed the low-level routine that calculates the G(T), to account for the v.4 variations. The proton rates are included in the calculation of the level p opulation. · plot_dem.pro To plot differential emission measure (DEM) values Unchanged. 70


Routines in the extra/ sub directory: · dens_plotter.pro A widget routine to allow the analysis of density sensitive ratios. Is now a wrapp er routine calling the widget RATIO_PLOTTER · temp_plotter.pro A widget routine to allow the analysis of temp erature sensitive ratios. Is now a wrapp er routine calling the widget RATIO_PLOTTER · g_of_t.pro To compute the G(T) of selected lines. A few keywords have b een added/ mo dified, mainly as an up date for V.4. · pop_plot.pro To plot nj Aj i/Ne values as a function of N
e

A few keywords have b een added/ mo dified, mainly as an up date for V.4. · show_pops.pro To display p opulations of significant levels in a CHIANTI ion mo del A few keywords have b een added/ mo dified, mainly as an up date for V.4. · emiss_calc.pro To compute the emissivities of all lines of a sp ecified ion over given ranges of temp erature and density. A few keywords have b een added/ mo dified, mainly as an up date for V.4. · integral_calc.pro To compute the atomic data integral for use in column or volume emission measure work. A few keywords have b een added/ mo dified, mainly as an up date for V.4.

B

Incorporating proton rates into CHIANTI

This section describ es the changes applied to the CHIANTI database and software in order to include the proton rates.

B.1

The proton rate data files

The proton rate data files have suffices .psplups and have the following format 2 3 2 0.000e+00 1.027e-02 8.000e+02-2.150e-13 1.052e-13 4.397e-12 \ 2.232e-11 5.389e-11 8.708e-11 1.014e-10 7.658e-11-2.805e-12 (The \ indicates a break in the line.) Note that the Z and sp ectroscopic numb er are not given for each ion, in contrast to the electron files. The rest of the line is the same as that for the electron files, except in this case there are 9 spline values as a 9-p oint spline was fitted to the data.

71


B.2

Reading the .psplups file

This is done by the routine read_splups.pro which loads the data into an IDL structure. The call is IDL> read_splups_ns, filename, splstr, splref , /prot The structure splstr has the following tags .lvl1 .lvl2 .t_type .gf .de .c_ups .nspl .spl lower level index upper level index transition type gf value Delta-E for transition (rydbergs) the scaling parameter number of spline points Vector of length 9, containing spline points

B.3

Changes to p op solver.pro

The routine pop_solver solves the set of linear equations that determine the level balance of the ion. To include proton rates, an extra matrix containing the proton rate co efficients needs to b e added to the equations. This matrix is created within pop_solver from the splstr structure mentioned ab ove. Note also that the same routine is used to descale the spline fits into proton rates as to descale the electron spline fits. This routine is descale_all.pro and is called as descale_all, temp, splstr, index, ups where temp can b e an array of temp eratures.

B.4

Implementing proton rates in user-written routines

User-written routines can b e mo dified to include proton rates through two steps. For routines which do not directly call pop_solver, the only changes are to add the keywords noprot=noprot, abund_file and ioneq_file to the routines' argument list, and to the call to the routine that calls pop_solver. For routines that directly call pop_solver, the following steps need to b e followed. The first is to add the keyword noprot=noprot to the routine's argument list. The second is to add a common blo ck analogous to those that already exist for the energy level, radiative and electron collision data. This common blo ck is COMMON proton, pstr, pe_ratio The third step is to add a line which will read the data. This is

72


if keyword_set(noprot) then begin pstr=-1 endif else begin read_splups, pname, pstr, pref, /prot endelse Before the call to pop_solver, the proton to electron ratio must b e evaluated. This is done with pe_ratio=proton_dens(temp) where temp contains the logarithm of the temp eratures that will b e passed to pop_solver.

B.5

The proton-to-electron ratio

To include the proton rates in CHIANTI it is necessary to know the proton numb er density Np . This quantity is usually expressed in terms of the ratio relative to the electron density. For a standard solar plasma this is a constant for temp eratures b eyond log T = 4.6 with a value around 0.85. Thus one option is to simply fix the ratio as a constant. As we want CHIANTI to b e applicable for low temp erature plasmas, however, we have decided to explicitly calculate the ratio making use of the ion balance and abundance files, that uniquely determine Np . The relevant routine is PROTON DENS.PRO. Np is calculated from the ion balance and element abundance files contained in CHIANTI through the following expression R(T ) = Np = Ne
n i=1

Ab(H)F (H+ , T ) +Z i Z =1 Z F (Ai , T )Ab(Ai )

(37)

where Ab is the element abundance, Ai is the ith element (i.e., A1 =H, A2 =He, etc.), Z is the charge on the ion, F (A+Z , T ) is the fraction of ions of element Ai in the form A+Z at i i temp erature T . The ion fractions contained in CHIANTI are tabulated over the range 4.0 log T 8.0. Ab ove and b elow these values, we set R(T ) to the values for log T = 8.0 and log T = 4.0, resp ectively. The use of this routine has some side effects. Some routines for which the ratio may have some effects in the results don't require you to select the ion balance or abundance files. E.g., DENSITY RATIOS.PRO do es not require the user to select these files, however, at low temp eratures one may see significant changes take place in line ratios on account of the change in the proton-to-electron ratio. We deal with this effect by using the default !abund\_file and !ioneq\_file files to derive the proton-to-electron ratio, but allowing the files to b e directly sp ecified by the user through keywords if he/she needs to do this. B.5.1 Implementing proton rates in user-defined pro cedures

We have mo dified the CHIANTI routines so as PROTON DENS.PRO is called once at the b eginning of the routine and the ratio data are passed to POP SOLVER.PRO through a common blo ck. 73


The mo difications due to the proton-to-electron ratio in user-defined pro cedures are as follows: · Extend the PROTON common blo ck to include ratio data. common proton, pstr, pe_ratio · If the ELEMENTS common blo ck do es not already exist in the routine, then it must b e added COMMON elements,abund,abund_ref,ioneq,ioneq_t,ioneq_ref · Call PROTON DENS.PRO to get the ratio pe_ratio=proton_dens(temp) The call to PROTON DENS.PRO thus do es not take place within POP SOLVER.PRO

C

Incorporating 9 point spline fits into user-defined procedures

This section describ es the changes in the IDL software required to incorp orate the 9-p oint spline fits.

C.1

Data file format changes

The mo dification to the .splups file is simple. Any transitions which are fitted with a 9-p oint spline will simply have four extra numb ers placed on the end of the data line. Transitions fitted with a 5-p oint spline will b e output as normal. Both 5 and 9-p oint fits can b e found in the same .splups file.

C.2

Changes to existing software

This section describ es the changes to the read_splups routine, and also the changes required to routines that call directly or indirectly read_splups. For some routines (such as synthetic, ...?) the reading of the data files is delegated to the routine setup_ion.pro. The data is then transferred to the main routine via common blo cks.

74


C.2.1

Routines that call read splups

Every routine that makes a call to read_splups.pro has to b e mo dified. Two changes are needed: 1. the call to read_splups 2. the upsilon common blo ck which contains the spline data The read_splups call used to b e read_splups,upsname,t_type,gfu,deu,c_ups,splups,upsref The new call is read_splups, filename, splstr, splref [, /prot] where /prot should b e set if proton rates are to b e read. The original common blo ck had the form COMMON upsilon,t_type,deu,c_ups,splups The new one should b e COMMON upsilon, splstr C.2.2 read splups

This reads data from .splups or .psplups files into an IDL structure (the previous version read data into several individual arrays). The call is IDL> read_splups, filename, splstr, splref [, /prot] The structure splstr has the following tags .lvl1 .lvl2 .t_type .gf .de .c_ups .nspl .spl lower level index upper level index transition type gf value Delta-E for transition (rydbergs) the scaling parameter number of spline points Vector of length 9, containing spline points

75


C.2.3

descale all.pro

This routine directly replaces descale_ups.pro in the CHIANTI software. It is called as descale_all, temp, splstr, index, ups An imp ortant difference is that the temp erature is sp ecified directly whereas previously the scaled temp erature was given. In addition, several temp eratures can b e given at once rather than just one. Note that there is no difference in how this routine treats the descaling of proton rates. The only place in the CHIANTI software where this routine is called is in pop_solver.pro. C.2.4 p op solver.pro

The way electron excitation rates are included in pop_solver has b een changed. Only a single for lo op is required now as the routine go es through each line in the structure. In addition, the routine can now descale the upsilons for several temp eratures simultaneously.

D

The extra set of complementary routines

This section describ es the features of the routines that are contained in the extra/ directory and that were contributed by Peter Young: · dens_plotter.pro A widget routine to allow the analysis of density sensitive ratios. · temp_plotter.pro A widget routine to allow the analysis of temp erature sensitive ratios. · g_of_t.pro To compute the G(T) of selected lines. · pop_plot.pro To plot nj Aj i/Ne values as a function of N
e

· show_pops.pro To display p opulations of significant levels in a CHIANTI ion mo del · emiss_calc.pro To compute the emissivities of all lines of a sp ecified ion over given ranges of temp erature and density. · integral_calc.pro To compute the atomic data integral for use in column or volume emission measure work. These routines, describ ed in more detail in Sect. D.2 b elow, have slightly different units of outputs, compared to the other routines.

76


D.1

Definitions

First of all, Sect. 8 gives the theory b ehind the interpretation of optically-thin emission lines which serves to set out the notation used here. Going back to Eq. 2, we write Ni = 0.83 F (T ) Ab(X) Ne ni , (38)

where F (T ) is the ionisation fraction (indep endent of Ne in current ion balance calculations), Ab(X) the abundance of the element relative to hydrogen, and the ratio of hydrogen to free electrons has b een taken as 0.83, as hydrogen and helium are completely ionised for temp eratures T > 104 K. The emissivity of the emission line resulting from a j-to-i radiative decay is defined as
ij

= E Nj A

ji

(39)

and has units of erg cm-3 s-1 . Often the alternative notation will b e used where is the wavelength of the emitted radiation in Angstroms (° and = 1.986 â 10-8 /E for E in A), ergs. We will also define the ion emissivity as ij = E nj Aji . (40)

In order to relate the emissivity to the actual observed intensity of a line, we make use of the third assumption, which tells us that the intensity is prop ortional to the emissivity of the plasma, and so P = (41) dV , where P is the p ower in an observed line (units: erg s-1 ), and dV is a volume of plasma with temp erature T and density Ne . Expanding using Eqs 38 and 39 gives P = 0.83 E Ab(X) F (T ) nj Aji Ne dV . (42)

An imp ortant feature of emission measure studies is to isolate those lines for which nj Aji Ne . By analysing only such lines, we are essentially separating the determination of the emission measure from the determination of the plasma density. If the lines all had different density dep endencies, then it would b e necessary to determine the density variation with temp erature b efore finding the emission measure. If the nj Aji Ne relation is assumed then we write 2 P = E Ab(X) G (T ) Ne dV (43) where G (T ) = 0.83 F (T ) nj A Ne
ji

(44)

which is the so-called `G-of-T' function. On account of the ionisation fraction F (T ) this function is sharply p eaked, and a common approximation (e.g., Pottasch [3], Jordan & Wilson [1]) is to assume that G(T ) has a constant value over a narrow temp erature interval around G(Tmax ), where Tmax is the temp erature of 77


maximum ionisation for the ion. Here we will use the temp erature of maximum emission or Tmem which is the temp erature at which G has its maximum. Defining G we require that so C = Our expression for P thus b ecomes P = E Ab(X) C E M (V ) where E M (V ) =
i V 2 Ne dV
i

,0

(T ) =



C 0



|log T - log T

mem

| < 0.15 (45) | > 0.15 (46) . (47)

|log T - log T G

mem

G (T )dT =

,0

(T )dT

T

mem

G (T )dT (100.15 - 10

-0.15

)

(48)

(49)

is the volume emission measure. Each volume Vi contains plasma with temp eratures such that |log T - log Tmem | < 0.15, and the sum over i is required in case there are distinct regions along the line of sight that satisfy this condition on T . Now, solar emission lines are often measured as intensity (or radiance), I , with units typically of erg cm-2 sr-1 s-1 . This quantity is related to P by P = 4 I dA (50)

where dA is the pro jected area of the emitting element. One thus relates the observed intensity to an emission measure by 4 I = E Ab(X) C E M (s) (51)

where E M (s) is the column emission measure, where s is the line-of-sight depth of the emitting region. Stellar emission lines are measured in flux (or irradiance), E , with units typically of erg cm-2 s-1 . E is related to P by P = 4 d2 E (52)

where d is the distance to the ob ject. The observed flux is then related to the emission measure by 1 E Ab(X) C E M (V ). (53) 4 d2 If one treats the emitting region as a uniform, spherical shell of thickness h then dV = 4 R2 dh (R the distance from the star centre of the shell; typically R = R , the radius of the star) and so the expression for E b ecomes E= 78


2 1 R E Ab(X) C E M (h). (54) 2 d2 where E M (h) is the emission measure over height. The factor 1/2 denotes that half the photons from the shell are emitted towards the stellar surface and so are destroyed. Jordan and co-workers (see, e.g., Jordan & Wilson [1], Jordan & Brown [2]) utilise this definition and an assumption of spherical symmetry to deduce energy balance relations in solar and stellar atmospheres.

E=

D.2

The primary routines

The routines are divided into primary and secondary routines. The secondary ones are called by some of the primary routines, and chances are that you won't have to use them to o often. They are describ ed in Sect. D.3. All of the routines have headers which give more detailed information ab out how they work. This header can b e read in the normal IDL way through, e.g., doc_library,'ratio_plotter'. D.2.1 p op plot.pro 1020 E nj Aji /N
e

This routine plots the values of (55) against Ne . As discussed in Sect. 8, if we only study lines in the emission measure analysis for which this quantity is indep endent of density, then the derived emission measure is indep endent of the plasma density. Example: For Fe XI I I, select a line/blend from lines in the range 200 to 205 ° A pop_plot,26,13,wrange=[200,205] Note how no single line shows zero density dep endence, and so care should b e taking in using Fe XI I I in emission measure analyses. Compare with Fe XVI: pop_plot,26,13,wrange=[330,370] where b oth the 335 and 360 lines are OK. D.2.2 integral calc.pro

This routine calculates C , defined in Eq. 47. It displays b oth this value and the values of E C and 4 /E C . For lines for which nj Aji Ne , C is insensitive to Ne , but for other lines Ne should b e sp ecified. Note that for blended lines only E C and 4 / E C are output. The routine also outputs the Tmem of the lines, accurate to 0.02 dex. Example: Work out C for the Fe XI I I lines b etween 200 and 205 ° at a density of 109 cm-3 . A integral_calc,26,13,wrange=[200,205],dens=9.

79


From Eq. 51, an observed line intensity of 100 erg cm-2 s-1 sr-1 for the 202.044 line implies a column emission measure of E M (s) = 100 â 1.614 â 1020 /Ab(F e), where 1.614 â 1020 is taken from 4pi/DE*C lambda column of the output. For Fe XIV, one can do: integral_calc,26,14,wrange=[210,220],dens=9. and so to get the same column emission measure for Fe XIV 211.32, an intensity of 100 â 1.614 â 1020 /2.280 â 1020 = 70.8 erg cm-2 s-1 sr-1 is required, where 2.280 â 1020 is the value of 4pi/DE*C lambda for Fe XIV 211.32. D.2.3 temp plotter.pro and dens plotter.pro

Both temp\_plotter.pro and dens\_plotter.pro call a widget-based routine (ratio_plotter, via the keywords /temp and /dens) that allows the thorough investigation of density or temp erature sensitive ratios. Observed line intensities can b e input for line ratios, and densities or temp eratures derived. Example: to study density sensitive ratios of Fe XI I I, simply typ e in dens_plotter,'fe_13' Try inputting some line intensities and errors from the SERTS-89 sp ectrum (Thomas & Neup ert [4]), and comparing the derived densities with those found by Young, Landi & Thomas [5] in Table 20. D.2.4 show p ops.pro

Gives p ercentage level p opulations for all levels within the sp ecified ion that have p opulations greater than 0.01%. Example: Compute level p opulations for Fe XI I I at a density of 10 show_pops,26,13,dens=10 D.2.5 g of t.pro
10

cm-3 :

Eq. 44 gives the definition of the contribution function as calculated by the g of t routine. In it's default setting g of t.pro actually calculates: E G (T ) = 0.83 E F (T ) nj A Ne
ji

which is more useful when considering blends of lines at different wavelengths. The E can b e `disabled' with the /no_de keyword. It is also useful to multiply the ab ove function by the element abundance, and this is accomplished with the /abund keyword. The output function is tabulated over 4.0 log T 8.0 at 0.1 dex intervals. For smaller intervals, see the ion interp routine. Examples: 80


result=g_of_t(26,13,dens=9.) result=g_of_t(26,13,wrange=[200,205],/abund) result=g_of_t(26,13,/no_de) One can also use this routine to derive the T ion_interp.pro routine, e.g., result=g_of_t(26,13,dens=9.) ion_interp,t,result,ti,g_ti,10 print,ti(where(g_ti eq max(g_ti))) result is tabulated at 0.1 dex intervals in temp erature. ion_interp interp olates result and in this case gives it at 0.01 dex intervals.
mem

of the emission line, by way of the

D.3

The secondary routines

These routines are called by the routines ab ove. D.3.1 emiss calc.pro

Calculates the ion emissivity (Eq. 40) for all transitions within the CHIANTI mo del of the ion. The returned data is in the form of a structure. The default is to calculate emissivities for temp eratures Tmax and log Tmax ± 0.15, and densities log Ne = 8.0, 8.5, 9.0, ...., 12.0. Example: emiss=emiss_calc(26,13) D.3.2 emiss select.pro

Allows the selection of lines/blends from the emiss structure created by emiss calc.pro. This routine is useful if you want to access the emissivities of lines directly, e.g., emiss=emiss_calc(26,13) em202=emiss_select(emiss,wra=[200,205],sel_ind=sel_ind) In this example, calling emiss select yields a widget that allows one to select a line/blend from the 200­205 ° range. The emissivities of this line blend will b e contained in em202, A while the emiss index/indices of this line/blend will b e contained in sel_ind. D.3.3 ion interp.pro

When reading the ionisation equilibrium files, you will receive an array with absolute (as opp osed to log) ion fractions tabulated at 0.1 dex intervals from log T = 4.0 to 8.0. A common need is to interp olate this data and obtain the ion fraction tabulated at smaller intervals. As the ion fractions are generally sharply p eaked, normal interp olation will lead to negative ion fractions at several temp eratures, and so a more satisfactory metho d is to 81


interp olate the log of the ion fraction. However, you need to take the log of only the non-zero values of the ion fraction. The several lines of co de required to p erform the interp olation are straightforward but irritating (when typ ed on many o ccasions!), and so this routine p erforms the task. Example: Use g of t to create a G(T ) function for one of the Fe XI I I lines, result=g_of_t(26,13,dens=9.) ion_interp,t,result,ti,g_ti,5 The G(T ) function is now tabulated at 0.02 dex intervals. Note that if t is not sp ecified, it is assumed to b e a vector going from 4.0 to 8.0 in 0.1 dex intervals.

E

More details

More details are found in the program headers (see the html version of this guide).

E.1

The CHIANTI line intensities structure

The tags of the line intensities structure are:

.lines

A structure containing information about the lines. Its size is the number of lines in the spectrum. The tags are: .iz .ion .snote .ident The atomic number of the elements (e.g., 26=Fe) The ionisation stage (e.g., 13=XIII) The identification of the ion (e.g., 'Fe XXIV d') The identification of the transition, configuration and terms in text form.

.ident_latex The identification of the transition, configuration and terms in latex form. .lvl1 The lower level of the transition (see .elvlc file for ion) The upper level for transition.

.lvl2

82


.tmax

The temperature of maximum emission of the line. If the G(T) are output, tmax is the maximum of G(T). If the isothermal approximation is used tmax=0.

If a DEM is used, tmax is the maximum of the emissivity that includes the product of the ion fraction and the DEM. Rounded to nearest 0.1 .wvl .flag Wavelength of the transition, in Angstroms. A flag, =-1 if the line has only theoretical energy levels. Otherwise flag=0. Intensity of line (erg/cm2/s/sr or phot/cm2/s/sr), divided by the element abundance (exclusive with .goft). The G(T) of the line (optional /exclusive with .int).

.int

.goft

.ioneq_name .ioneq_logt .ioneq_ref .dem_name .dem .dem_logt .dem_ref .model_name

The ion balance file used (full path). The Log10 T values associated. The references. The differential emission measure file eventually (full path). The Log10 DEM values The Log10 T values associated. The references. A string indicating the model used: 1- Constant density 2- Constant pressure 3- Function (Te,Ne) used

.model_file .model_ne

Full path of the (Te,Ne) file if defined. Null string otherwise. the Ne value(s). - a scalar if 'Constant density' is selected. - an array if 'Function' is selected. - 0. if constant pressure is selected. 83


.model_pe

the Pe value. - a scalar if constant pressure is selected. - 0. if 'Constant density' is selected. - an array=density*temperature if 'Function' is selected.

.model_te .wvl_units .wvl_limits .int_units

the Te values if 'Function' is selected. Otherwise 0. The wavelength units. The wavelength limits specified by the user. The intensity units (erg/cm2/s/sr or phot/cm2/s/sr) if intensities are calculated, otherwise the G(T) units (erg cm3/s/sr or phot cm3 /s/sr)

.logt_isothermal The Log10(T) values used. .logem_isothermal The Log10(EM) values used. .date .version The date and time when the structure was created. The version number of the CHIANTI database used.

.add_protons A flag (0/1) to indicate whether proton data were used (1) or not (0) to calculate the level population. .photoexcitation A flag (0/1) to indicate if photoexcitation was included (1) or not (0). .radtemp The blackbody radiation field temperature used (if photoexcitation was included). .rphot Distance from the centre of the star in stellar radius units (if photoexcitation was included).

84


E.2

The CHIANTI sp ectrum structure

The sp ectrum structure output of MAKE CHIANTI SPEC has the following ADDITIONAL tags (compared to the tags of the CHIANTI line intensities structure created by CH SYNTHETIC:

LAMBDA SPECTRUM UNITS WRANGE INSTR_FWHM BIN_SIZE ABUND_NAME ABUND MIN_ABUND ABUND_REF CONTINUUM FILE_EFFAREA EFFAREA

The array of X-values The array of Y-values The units of LAMBDA, SPECTRUM The wavelength range The Instrumental FWHM Width of the Bins (fixed) in angstroms The CHIANTI abundance file name The abundance values The minimum abundance value used The references The values of the continuum (if calculated) The Effective Area File used (optional) The array of effective area values (optional - same size of LAMBDA)

.LINES

.PEAK

An array of structures, for all the lines used to calculate the SPECTRUM. The tags are the same as those created by CH_SYNTHETIC, plus The peak intensity of the line in the spectrum (approx. value)

85