Subject, Problems and Objects of Theoretical Astrophysics. ... Stellar Photospheres, Their Features. ... Physics of Continuous Radiation Absorption in Stellar Photospheres. ... Continuous Radiation Absorption in Stellar Photospheres of Various Spectral Classes. Solar Type Photospheres. ... Characterisics of Absorption Lines. ... Interstellar Absorption Lines, Their Features. ... Physical and Dynamic Features of Interstellar Medium, Which Follows from Observations of Interstellar Absorption Lines. ...

We present the detection and analysis of molecular hydrogen emission towards ten interstellar regions in the Large Magellanic Cloud. We examined low-resolution infrared spectral maps of 12 regions obtained with the Spitzer infrared spectrograph (IRS). ... The excitation diagrams of the detected H2 transitions are used to determine the warm H2 gas column density and temperature. ... We find the excitation of H2 by this process is equally efficient in both atomic- and molecular-dominated regions. ...

The Arcetri Spectral Code (Landi and Landini 1998) allows to evaluate the spectrum of continuum and line radiation emitted by hot and optically thin plasmas in the spectral range 1-2000 Angstrom. The Code is composed by a large database of atomic data and transition probabilities for calculating spectral line emissivities and a suite of fortran programs able to evaluate free-free, free-bound and two-photon continuum radiation. ... To get he Arcetri Spectral Code related publications . ...

This JAVA interface gives the possibility for working with the radio emission data of radio sources in clusters of galaxies from the Cluster database. ... For this, after loading the document with optical (or radio) data for the requested cluster, click on [ radio spectra (1.2 or 1.1)] in the top line of the document and then choose interface version which is compatible with your Internet-browser. ... For more information about the JDK support in the browsers see Java for browsers . ...

... The models provided are: . abs - absorption of x-rays by neutral gas with solar abundances. parameter 1 = . ... parameter 2 = . ... normalization - logarithmic value of the flux density at 1 keV in units of keV cm -2 s -1 keV -1 . ... normalization - logarithmic value of the normalization of the gaussian in units of keV cm -2 s -1 . ... absorption ( params )* model ( params ) . ... A single value for the normalization (i.e., fixed normalization) will force the program to use that value. ...

... Molecular clouds are enmeshed in webs of diffuse atomic gas that contain important information about their formation and interaction with their environment, not least because the atomic gas can trace lower column densities that are unshielded from UV radiation. ... The GALFA H I sky survey of Galactic 21cm-line emission with the Arecibo L-band Feed Array has recently mapped the MBM 53-55 region with a 3.5-arcminute beam and 0.2 km/s channels. ... Other GALFA publications ...

Next: Radial velocity of the Up: Optical spectrum of IRAS04296 Previous: Observations and spectra reduction . ... However, molecular emission features are only very rarely observed in the optical spectra of PPNe. ... On the other hand, it is well known that cometary nuclei spectra show prominent Swan band emission. In both spectra of IRAS04296 we have discovered strong emission in the (0;0) and (0;1) bands of the Swan system of the molecule. ... Now consider the case of IRAS04296. ...

... Bojan Nikolic web pages (r. 329) . Understanding Infrared emission from galaxies . This page contains a description and links for download of software that may be used for modelling various aspect of absorption and emission of radiation by interstellar dust. ... Also, some basic modelling of radiation fields and similar supporting code . ... dust-1.0.1 . ... Modelling absorption and emission of radiation by interstellar dust . ... Copyright 2005 -- 2016, Bojan Nikolic feedback welcome ...

. The frequency of the spectral maximum f m of the gyrosynchrotron emission vs. the power-law index of the electron spectrum calculated according to Dulk & Marsh (1982). Curves are shown for various column densities LNe of accelerated electrons and magnetic field strengths B . The angle between the line of sight and the magnetic field is 45 degree.

... Dodson, Legge et al, ApJ, 2003 Spectral Line Sources · Requirement of high brightness temperatures means no thermal emission · Masers: Galactic Extragalactic · OH, H2O · OH, H2O, SiO, CH3OH · Galactic extra-galactic HI absorption VLBI arrays · VLBA (Very Long Baseline Array) Dedicated US array of ten 25m telescopes 330 MHz ­ 90 GHz · EVN (European VLBI Network) Formal collaboration of radio telescopes in Europe, Asia and South Africa ~15 telescopes 15m to 100m 330 MHz ­ 22/43 GHz ...

Next: Structure of the Galaxy Up: Model of the Galaxy Previous: Model of the Galaxy . As discussed above (Section  6 ), galactic binary systems are assumed to be distributed logarithmically along their semi-major axis A (Abt and Levy, 1976[ 2 ]), . ... Figure 40: Number of binary stars per frequency decade. ... As the observed distribution of binary periods is flat (equation ( 15.3.1 )), the normalization constant is the total number of galactic binaries per frequency decade: . ...

... Galaxies 99 Cosmic background with model of cloudy interstellar medium Yu. ... Figure 1: Averaged spectrum of the cosmic background I f in frequency range 0.25 200 MHz for the Galactic poles. ... First interpretation of the cosmic noise background spectrum at broad band frequency range 0.25 200 MHz with a model of the cloudy interstellar medium ISM is presented here. ... Synthesized background spectra I f for regions of the Galactic poles at the frequency range 0.25 200 MHz is presented in Fig. ...

These are very prominent absorption lines is most all galaxies. ... These pair of absorption lines will appear in all the spectra and they should be your principle source for determining the redshift. ... When this applet opens you will see an iconic representation of galaxies in the left hand side of the applet and a target area in the right side of the applet. ... Note: What you are doing in this excercise is identical to what Hubble did in the 1920's and you are using the same galaxies. ...

... Geomagnetic field lines can guide energetic electrons and protons from magnetosphere or magnetosheath down to Earth's atmosphere . Precipitating particles loose their energy via collisions with the neutral particles and ionize them at approximately the same altitude range than solar UV radiation when creating the ionosphere . In addition, some of the atmospheric constituents are excited to higher energy levels: this can lead to emission of auroral light. ... ISPEC page on aurora . ...

Next: Participant List . ... Table of Contents - Index . Cover Illustration: This figure, from the paper by Gary Ferland, Kirk Korista, and Dima Verner , summarizes the results of thousands of complete spectral synthesis calculations performed with the Cloudy program. ... These calculations show that this line-one of the strongest quasar emission lines-is produced efficiently only over a narrow range of physical conditions. ...

Astronomical Data Center . ... You can access the files described here in three ways: . ... Use CDS' VizieR Service at ADC to explore the data files. ... Get the data files via anonymous FTP. ... 1981) -------------------------------------------------------------------------------- Byte-per-byte Description of file : table1a Byte-per-byte Description of file : table1b -------------------------------------------------------------------------------- Bytes Format Units Label Explanations ...

Using Ly alpha line profiles generated from a grid of M dwarf model atmospheres we calculate the attenuation factor [i.e. Ly alpha (obs)/ Ly alpha (intrin)] due to the interstellar medium as a function of hydrogen column density. ... The major uncertainty in this work has been the interstellar hydrogen column density, emphasizing the need for further work in this area and in particular an accurate model of its variation in all directions. ...

... Fitting the observed dependence includes calculations of the polarization cross-sections averaged over particles orientation and size distribution, their normalization and the comparison of obtained dependencies with Serkowski's curve representing observational data for a chosen star. ... Variations of the polarization factors with wavelength are shown in Fig. 16 for homogeneous spheroidal particles with PF orientation. ... The distinction between prolate and oblate spheroids is also clearly seen. ...

... For eight samples of main-sequence disk stars, the metallicity indices 0.6 , R-1 (U-V), m1 ( ) have been calculated. The indices 0.6 and (U-B) have been calibrated to the metal abundance [Fe/H] for the spectral types F, G and K separately. ... It is found that the UBV and RI data for F- and K-dwarfs imply that the metallicity of the Sun coincides with that found for the Hyades, whereas the G-dwarfs give the well known smaller metallicity of the Sun with respect to the Hyades. ...

... 1998: . The structure of neutral interstellar hydrogen emission at high galactic latitudes from 45 to 90 degrees was studied for the first time with the RATAN-600 at a wavelength of 21cm. The on galactic latitude dependence of the average characteristics of hydrogen distribution in the sky corresponds to the distribution of gas in the Galaxy in the shape of a flat layer. ... Archive . ...