#stellarspectra — Public Fediverse posts
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Theory Of Stellar Spectra by V.V. Sobolev
The only source of our information on stars is their radiation. From stellar spectra we judge the structure of stellar atmospheres, their chemical composition, and physical processes taking place there. Spectrograms are interpreted on the basis of the theory of stellar spectra, wherein lies its enormous value for astrophysics. Until recently astronomers could observe stellar radiation only in a very small range of frequencies making up the visible region of the spectrum. However, about 20 years ago radio astronomy came into being which permits investigating the radiation of celestial bodies in a completely different spectral region.
Quite recently, in connection with the launching of satellites and rockets, there arose the theoretical possibility of obtaining stellar spectra in any frequency range. So far, highly useful spectrograms of stars and the sun have been obtained in the so-called rocket ultraviolet. It is obvious that this broadening of observational data will even further increase the significance of the theory of stellar spectra. At the same time it is necessary to improve and extend this theory.
The surface layers of stars, out of which their spectra arise, represent
strongly ionized gases, i.e., plasma. Plasma studies are also being carried out in physics laboratories, having increased in intensity of late. Methods used by physicists in studying plasmas are in many respects similar to methods used by astrophysicists in studying stellar atmospheres. Therefore, the theory of stellar spectra is of interest not only to astrophysicists but also to physicists.An excellent example of the broad interest in the theory of stellar spectra is the summer seminary on problems of this theory, organized by the
Astronomical Council of the Academy of Sciences of the USSR and the Leningrad University and held in Leningrad in June 1964* About 150 young astrophysicists and physicists of the Soviet Union participated in the sessions. This book was written on the basis of the lectures given at that time.
The first part of the book examines atomic processes associated with the
formation of spectra, with special emphasis on calculation of the energy levels of the atom and the probability of transitions between these levels. The second part deals with the theory of radiation transfer, which forms an important aspect of the theory of stellar spectra. The next two parts discuss the most essential problems in the formation of spectra of different types of stars and nebulae. The last part, devoted to ultraviolet spectra of celestial bodies, mainly gives a review of observational data and their qualitative interpretation (since, as yet, no quantitative theory of these spectra has been established).
The diversity of the problems of the modern theory of stellar spectra makes it impossible to present them with sufficient completeness in a single monograph.
The authors of this book have endeavored to acquaint the reader with the most important of these problems.You can get the book here and here
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Preface …………………………………………… iii
PART I. PHYSICAL PROCESSES CONNECTED WITH THE FORMATION OF SPECTRA ………… 1
Plasma Spectroscopy (S.E. Frish) …………………….. 1
Calculations of Atomic Energy Levels (A.P. Yutsis and Ya.I. Vizbarayte) …………… 23
Theory of Atomic Transitions (G.F. Drukarev) ……….. 35PART II. THEORY OF RADIATIVE TRANSFER ……………………… 64
Certain Nonlinear Problems of the Theory of Radiative Transfer (V.A. Ambartsumyan) ……. 64
Radiative Diffusion in Gases (V.V. Sobolev) …………. 75
Determination of the Populations of Excited Levels in an Optically Thick Gas Layer (V.V. Ivanov) ……….. 92
Nonstationary Radiation Field (I.N. Minin) …………. 116
Randomized Problem of Diffuse Reflection (R.V. Ambartsumyan) ………… 135PART III. SPECTRA OF FIXED STARS ……………………….. 140
Models of Stellar Atmospheres (V.V. Sobolev) ………. 140
Continuous Spectra of Hot White Dwarfs (A.K. Kolesov) ……. 147
Model Atmospheres of Main-Sequence Stars of Class M (V.G. Buslavskiy) …….. 152
Determination of the Chemical Composition of Stellar Atmospheres (A.A. Boyarchuk) ……….. 160PART IV. SPECTRA OF NONSTATIONARY STARS AND INTERSTELLAR MATTER ………… 170
Spectra of Nonstationary (Variable) Stars (V.G. Gorbatskiy) ……….. 170
Analysis of the Emission Spectra of Nonstationary Stars (A.A. Boyarchuk) ………… 194
Spectra of Interstellar Matter (S.A. Kaplan) ………… 203
Radio Observations of Planetary Nebulae (Yu. N. Pariyskiy) ………. 216PART V. SPECTRA OF CELESTIAL BODIES IN THE FAR ULTRAVIOLET REGION ……….. 220
#astronomy #astrophysics #physics #quantumMechanics #radiativeTransfer #sovietLiterature #stellarSpectra #stellarStructure
Spectra of Celestial Bodies in the Far Ultraviolet Region (G.A. Gurzadyan) ………. 220 -
Theory Of Stellar Spectra by V.V. Sobolev
The only source of our information on stars is their radiation. From stellar spectra we judge the structure of stellar atmospheres, their chemical composition, and physical processes taking place there. Spectrograms are interpreted on the basis of the theory of stellar spectra, wherein lies its enormous value for astrophysics. Until recently astronomers could observe stellar radiation only in a very small range of frequencies making up the visible region of the spectrum. However, about 20 years ago radio astronomy came into being which permits investigating the radiation of celestial bodies in a completely different spectral region.
Quite recently, in connection with the launching of satellites and rockets, there arose the theoretical possibility of obtaining stellar spectra in any frequency range. So far, highly useful spectrograms of stars and the sun have been obtained in the so-called rocket ultraviolet. It is obvious that this broadening of observational data will even further increase the significance of the theory of stellar spectra. At the same time it is necessary to improve and extend this theory.
The surface layers of stars, out of which their spectra arise, represent
strongly ionized gases, i.e., plasma. Plasma studies are also being carried out in physics laboratories, having increased in intensity of late. Methods used by physicists in studying plasmas are in many respects similar to methods used by astrophysicists in studying stellar atmospheres. Therefore, the theory of stellar spectra is of interest not only to astrophysicists but also to physicists.An excellent example of the broad interest in the theory of stellar spectra is the summer seminary on problems of this theory, organized by the
Astronomical Council of the Academy of Sciences of the USSR and the Leningrad University and held in Leningrad in June 1964* About 150 young astrophysicists and physicists of the Soviet Union participated in the sessions. This book was written on the basis of the lectures given at that time.
The first part of the book examines atomic processes associated with the
formation of spectra, with special emphasis on calculation of the energy levels of the atom and the probability of transitions between these levels. The second part deals with the theory of radiation transfer, which forms an important aspect of the theory of stellar spectra. The next two parts discuss the most essential problems in the formation of spectra of different types of stars and nebulae. The last part, devoted to ultraviolet spectra of celestial bodies, mainly gives a review of observational data and their qualitative interpretation (since, as yet, no quantitative theory of these spectra has been established).
The diversity of the problems of the modern theory of stellar spectra makes it impossible to present them with sufficient completeness in a single monograph.
The authors of this book have endeavored to acquaint the reader with the most important of these problems.You can get the book here and here
Follow us on
Twitter https://x.com/MirTitles
Mastadon https://mastodon.social/@mirtitles
Bluesky https://bsky.app/profile/mirtitles.bsky.social
Tumblr https://www.tumblr.com/mirtitles
Internet Archive https://archive.org/details/mir-titles
Fork us on gitlab https://gitlab.com/mirtitles
Preface …………………………………………… iii
PART I. PHYSICAL PROCESSES CONNECTED WITH THE FORMATION OF SPECTRA ………… 1
Plasma Spectroscopy (S.E. Frish) …………………….. 1
Calculations of Atomic Energy Levels (A.P. Yutsis and Ya.I. Vizbarayte) …………… 23
Theory of Atomic Transitions (G.F. Drukarev) ……….. 35PART II. THEORY OF RADIATIVE TRANSFER ……………………… 64
Certain Nonlinear Problems of the Theory of Radiative Transfer (V.A. Ambartsumyan) ……. 64
Radiative Diffusion in Gases (V.V. Sobolev) …………. 75
Determination of the Populations of Excited Levels in an Optically Thick Gas Layer (V.V. Ivanov) ……….. 92
Nonstationary Radiation Field (I.N. Minin) …………. 116
Randomized Problem of Diffuse Reflection (R.V. Ambartsumyan) ………… 135PART III. SPECTRA OF FIXED STARS ……………………….. 140
Models of Stellar Atmospheres (V.V. Sobolev) ………. 140
Continuous Spectra of Hot White Dwarfs (A.K. Kolesov) ……. 147
Model Atmospheres of Main-Sequence Stars of Class M (V.G. Buslavskiy) …….. 152
Determination of the Chemical Composition of Stellar Atmospheres (A.A. Boyarchuk) ……….. 160PART IV. SPECTRA OF NONSTATIONARY STARS AND INTERSTELLAR MATTER ………… 170
Spectra of Nonstationary (Variable) Stars (V.G. Gorbatskiy) ……….. 170
Analysis of the Emission Spectra of Nonstationary Stars (A.A. Boyarchuk) ………… 194
Spectra of Interstellar Matter (S.A. Kaplan) ………… 203
Radio Observations of Planetary Nebulae (Yu. N. Pariyskiy) ………. 216PART V. SPECTRA OF CELESTIAL BODIES IN THE FAR ULTRAVIOLET REGION ……….. 220
#astronomy #astrophysics #physics #quantumMechanics #radiativeTransfer #sovietLiterature #stellarSpectra #stellarStructure
Spectra of Celestial Bodies in the Far Ultraviolet Region (G.A. Gurzadyan) ………. 220 -
Weekly Update from the Open Journal of Astrophysics – 07/06/2025
It’s Saturday so once again it’s time for the weekly update of papers published at the Open Journal of Astrophysics. Since the last update we have published two new papers, which brings the number in Volume 8 (2025) up to 69 and the total so far published by OJAp is now up to 304.
The two papers published this week, with their overlays, are as follows. You can click on the images of the overlays to make them larger should you wish to do so.
The first paper to report is “Chemical Abundances in the Leiptr Stellar Stream: A Disrupted Ultra-faint Dwarf Galaxy?” by Kaia R. Atzberger (Ohio State University) and 13 others based in the USA, Germany, the UK, Sweden, Australia, Canada and Brazil. This one was published on 2nd June 2025 and is in the folder marked Astrophysics of Galaxies. It presents a spectroscopic study of stars in a stellar stream suggesting that the stream originated by the accretion of a dwarf galaxy by the Milky Way.
The overlay is here:
You can read the final accepted version on arXiv here.
The second paper is “Scaling Laws for Emulation of Stellar Spectra” by Tomasz Różański (Australian Nastional University) and Yuan-Sen Ting (Ohio State University, USA). This was published yesterday, i.e. on 6th June 2025, and is in the folder Instrumentation and Methods for Astrophysics. The paper discusses certain scaling models and their use to achieve optimal performance for neural network emulators in the inference of stellar parameters and element abundances from spectroscopic data.
The overlay is here:
You can find the officially-accepted version of the paper on arXiv here.
That’s the papers for this week. I’ll post another update next weekend.
As a postscript I have a small announcement about our social media. Owing to the imminent demise of Astrodon, we have moved the Mastodon profile of the Open Journal of Astrophysics to a new instance, Fediscience. You can find us here. The old profile currently redirects to the new one, but you might want to update your links as the old server will eventually go offline.
#arXiv241017312v2 #arXiv250318617v2 #AstrophysicsOfGalaxies #DiamondOpenAcccess #InstrumentationAndMethodsForAstrophysics #MilkyWay #neuralNetworks #OpenJournalOfAstrophysics #spectroscopy #stellarSpectra #StellarStreams #TheOpenJournalOfAstrophysics
-
Weekly Update from the Open Journal of Astrophysics – 07/06/2025
It’s Saturday so once again it’s time for the weekly update of papers published at the Open Journal of Astrophysics. Since the last update we have published two new papers, which brings the number in Volume 8 (2025) up to 69 and the total so far published by OJAp is now up to 304.
The two papers published this week, with their overlays, are as follows. You can click on the images of the overlays to make them larger should you wish to do so.
The first paper to report is “Chemical Abundances in the Leiptr Stellar Stream: A Disrupted Ultra-faint Dwarf Galaxy?” by Kaia R. Atzberger (Ohio State University) and 13 others based in the USA, Germany, the UK, Sweden, Australia, Canada and Brazil. This one was published on 2nd June 2025 and is in the folder marked Astrophysics of Galaxies. It presents a spectroscopic study of stars in a stellar stream suggesting that the stream originated by the accretion of a dwarf galaxy by the Milky Way.
The overlay is here:
You can read the final accepted version on arXiv here.
The second paper is “Scaling Laws for Emulation of Stellar Spectra” by Tomasz Różański (Australian Nastional University) and Yuan-Sen Ting (Ohio State University, USA). This was published yesterday, i.e. on 6th June 2025, and is in the folder Instrumentation and Methods for Astrophysics. The paper discusses certain scaling models and their use to achieve optimal performance for neural network emulators in the inference of stellar parameters and element abundances from spectroscopic data.
The overlay is here:
You can find the officially-accepted version of the paper on arXiv here.
That’s the papers for this week. I’ll post another update next weekend.
As a postscript I have a small announcement about our social media. Owing to the imminent demise of Astrodon, we have moved the Mastodon profile of the Open Journal of Astrophysics to a new instance, Fediscience. You can find us here. The old profile currently redirects to the new one, but you might want to update your links as the old server will eventually go offline.
#arXiv241017312v2 #arXiv250318617v2 #AstrophysicsOfGalaxies #DiamondOpenAcccess #InstrumentationAndMethodsForAstrophysics #MilkyWay #neuralNetworks #OpenJournalOfAstrophysics #spectroscopy #stellarSpectra #StellarStreams #TheOpenJournalOfAstrophysics