The Arcetri Spectral Code (Landi and Landini 2002) 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. ... Landi, E., Landini, M., 2002, A , 384, 1124 . ...

Context. Thermal emission by stochastically heated dust grains (SHGs) plays an important role in the radiative transfer (RT) problem for a dusty medium. ... Aims: We define an appropriate problem for benchmarking dust emissivity calculations in the context of RT simulations, specifically including the emission from SHGs. ... It also includes a series of analytically defined radiation fields to which the dust population is to be exposed and instructions for the desired output. ...

... 8 February , 2014 SAI seminar (Ryde et al 2010) 5 Thermal emission from GRB jet progenitor observer photon jet Photosphere (=1) · · · · Photons are not produced at the photosphere We have to calculate radiative transfer We need to know where the photons are produced We construct the expression for effective optical depth in relativistic flow considering random walk process in relativistic flow SAI seminar 6 8 ... 8 February, 2014 SAI seminar 28 ...

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. ...

Next: Infrared Data Up: Contents Previous: Optical Photometry . ... For example, one method is to derive the spectral energy distribution (SED) for a target star and compare it to the SED of a dereddened standard star. ... Temperature can be determine via the B - V color (Gilliland 1985): . ... The results produced small extinctions to the background stars of between A and A . ... The most accurate extinction calculation requires both IR and spectral data. Infrared Data . Spectroscopic Data . ...

. 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.

... This matter may absorb the radiation from the source, scatter it or in fact emit fur ther radiation. ... For the case of a homogeneous cloud with a constant source function and optical depth with initial incident intensity , the emergent intensity is This makes a lot of sense: the emergent radiation is the sum of the incident intensity attenuated by the total optical depth plus the sum of each section of cloud emission attenuated by the optical ...

... This thesis sets out to explain this observation by the presence of optical non-thermal synchrotron emission, connected with the relativistic jet that powers the radio emission in these quasars. ... We find that about 40% of the sources have power-law SEDs, while a similar number show evidence for two primary components: a blue power law and optical synchrotron emission. The blue power law is similar to the dominant component observed in the spectra of optically-selected QSOs. ...

... From its application to the optical Carbon Mira R For we find that the temperature of the inner shell boundary exceeds 1000 K, ranging between 1200 K and 1400 K. The optical depth of the shell at 11.3 \mu m is determined at \tau_11 \mu m = 0.105 with T_eff = 3200 \pm 200 K for the central star in the considered phase of variability. ... We show that the optical and near-IR light curves are strongly affected by small changes of T_eff and of the shell optical depth with pulsation. ...

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. ...

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 . ...

... 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. ...

The database contains references to the papers, data files and links to the Internet resources related to measurements and calculations of the optical constants in the wavelength interval from X-rays to radio domain. ... References to some useful books and reviews on the subject (e.g. the classical handbooks edited by E.D.Palik) and links to Internet collections of optical constants and personal WWW pages with related software were also placed in the database. You have arrived at our welcome page. ...

... 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 . ...

... In laboratory the design and a manufacturing techniques mirror aspherical optics are developed ("fokon", ellipsoid, aspherical mirror).Such optical elements are made of widespread aluminium alloys on the standard equipment without use diamond turning. ... Using: optical blocks of not image optical devices for transitions, collimation, focus (concentration) radiations in a wide spectral range from UV to IR. Focusing and collimation of light; . ... circle aperture/ring aperture; . ... Back Forward . ...

... The discovery of this radiopulsar is potentially important not only for confirming the theory of evolution of NS, but also for understanding processes occurring in stellar winds   from normal stars. After all, a radiopulsar orbiting in the semi-transparent stellar wind of a normal star is a sort of probe scanning an inhomogeneous plasma by pulsed radiation (Lipunov and Prokhorov, 1984)[ 110 ]. ... 1) absorption of radio waves (light curve); . ... This object is a radiopulsar orbiting a Be-star. ...

... The Galactic low-mass X-ray binary GS 2023+338 was discovered during the burst on May 22, 1989 with the Japanise satellite Ginga (aka Galaxy). The flux reached 17 crabs (this unit of flux measurement is an bright X-ray source, Crab Nebula) at 10-35 keV. ... No other radio telescope worldwide carried out multi-frequency measurements. ... Upon 14 days the radio flux fell below the detection level at the RATAN-600 in relation to the decrease of the X-ray flux. ...

Calculation of Atmospheric Emission Measured by Gregorian Feed Horns Paul F. Goldsmith September 16, 2001 As we use higher frequencies, emission from the Earth's atmosphere becomes more sig- ni cant. ... To use this program, you input the altitude, temperature, and precipitable water vapor (pwv) in mm. ... I have run the ATM code for several values of pwv with plausible temperature, and generated the zenith sky temperature as a function of frequency between 1 and 15 GHz. ...

Astronomy Picture of the Day . ... 21.05.1997 . ... Palomar Observatory , 200-in Hale Telescope Explanation: New evidence bolsters once controversial claims that Gamma-Ray Bursts (GRBs) are the most powerful explosions ever found by humanity. Two weeks ago, an average GRB became instantly historic when prompt, coincident X-ray and optical emissions were identified. ... If GRBs do occur this far into our universe, then radio emission was predicted to peak about a week after the optical emission . ...

... Spectroscopy of Semiconductors and Dielectrics . ... Interband optical transitions and their optical properties. ... Excitons in crystals. ... Collective interaction effects in exciton and nonequilibrium high-density carrier system. ... Carrier spin and exciton optical orientation in semiconductors. ... Two-dimensional excitons in quantum wells and related quantum systems. €аState density in transverse magnetic field and effect of random potential fluctuation on one-particle spectrum shape. ...