Journal of Quantitative Spectroscopy & Radiative Transfer 183 (2016) 1–3

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Editorial Preface: Viktor V. Sobolev and his scientific legacy

The study of radiation processes in celestial objects is a talks by internationally recognized experts as well as a fundamental problem in . A powerful tool for memorial session. Original scientific results were pre- the solution of this problem is provided by the theory of sented during parallel sessions on: radiative transfer. One of the founding fathers of modern radiative transfer theory was the prominent full member  radiative transfer theory of the Russian (formerly Soviet) Academy of Sciences  interstellar matter Viktor Viktorovich Sobolev (Fig. 1).  stellar atmospheres, circumstellar matter, and planetary Academician Sobolev was born on 2 September 1915. atmospheres All his professional life was associated with the Saint  high-energy astrophysics and cosmology. Petersburg (formerly Leningrad) State University. From 1948 to 1988 he was the head of the Chair of Astrophysics. The program and the abstracts of conference presentations He passed away on 7 January 1999 at the age of 83. are available at the conference web site http://www.astro. For many years Viktor Sobolev was the leader of the spbu.ru/Sobolev100. renowned Leningrad/St. Petersburg school of theoretical With Elsevier's encouragement, we solicited full-size astrophysics founded by Academician Viktor Amazaspo- papers for a topical issue of the Journal of Quantitative vich Ambartsumian (Fig. 2). He made seminal contribu- Spectroscopy and Radiative Transfer (JQSRT) intended to pay tions to many fields of astrophysics. His best-known result is the famous so-called Sobolev approximation describing line formation in moving media such as envelopes of [1]. His classical monographs on radiative transfer in stellar and planetary atmospheres [2,3] have been quite influential and are still widely cited. Many Sobolev's results have become standard textbook material. Sobolev's Course in Theoretical Astrophysics (first published in 1967 and updated in 1975 and 1985) [4] has for many years been the main graduate textbook on theoretical astro- physics for students in the former USSR, , and other countries.

1. Memorial Sobolev conference

The 100th birthday anniversary of Academician Sobolev was celebrated by the astrophysics community on 2 Sep- tember 2015. In his honor, the State University organized the international conference on “Radiation Mechanisms of Astrophysical Objects: Classics Today” which was held from 21–25 September 2015 (Fig. 3). The conference highlighted recent advances in the research fields to which V. V. Sobolev had contributed so prominently. It included plenary sessions featuring review Fig. 1. Academician V. V. Sobolev. http://dx.doi.org/10.1016/j.jqsrt.2016.04.022 0022-4073 Published by Elsevier Ltd. 2 Editorial / Journal of Quantitative Spectroscopy & Radiative Transfer 183 (2016) 1–3 tribute to Academician Sobolev and commemorate his 2. Scientific organizing committee of the Sobolev scientific contributions. As always, every invited review conference and regular paper included in this topical issue has undergone the same rigorous peer-review process as any Yuri Yu. Balega (Special Astrophysical , other manuscript published in the JQSRT. Russia) Anatoly M. Cherepashchuk (Moscow State University, Russia) Nikolai N. Chugai (Institute of Astronomy, Russia) Rustam D. Dagkesamanskii (Pushchino Radio Astonomy Observatory, Russia) Stanislav I. Grachev (Saint Petersburg State University, Russia) Vladimir P. Grinin, Co-Chair (Pulkovo Observatory, Russia) Alexander F. Kholtygin, Secretary (Saint Petersburg State University, Russia) Moisey A. Livshits (Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Russia) Michael I. Mishchenko (NASA Goddard Institute for Space Studies, USA) Dmitrij I. Nagirner, Co-Chair (Saint Petersburg State University, Russia) Arthur G. Nikoghossian (Byurakan Astrophysical Observatory, Armenia) Juri Poutanen (Tuorla Observatory, Finland) Nail A. Sakhibullin (Kazan Federal University, Russia) Fig. 2. Academicians V. A. Ambartsumian and V. V. Sobolev. Boris M. Shustov (Institute of Astronomy, Russia)

Fig. 3. Participants of the memorial Sobolev conference. Editorial / Journal of Quantitative Spectroscopy & Radiative Transfer 183 (2016) 1–3 3

Rashid A. Sunyaev (Space Research Institute, Russia; and the Russian Foundation for Basic Research. MIM Max Planck Institute for Astrophysics, ) acknowledges financial support from the NASA/Goddard Lev Titarchuk (Universita Ferrara, Italy) Space Flight Center Community Service Fund managed by Tõnu Viik (Tartu Observatory, Estonia) David Leisawitz.

3. Local organizing committee of the Sobolev References conference [1] Sobolev VV. Moving envelopes of stars. Leningrad: Leningrad State Andrej V. Dementyev (Saint Petersburg State University Press; 1947 (in Russian). English edition: Cambridge, MA: Harvard University Press, 1960. University, Russia) [2] Sobolev VV. Transport of radiant energy in stellar and planetary Nazar R. Ikhsanov (Saint Petersburg State University, atmospheres. Moscow: Gostekhizdat; 1956 (in Russian). English Russia) edition: A treatise on radiative transfer. Princeton, NJ: Van Nostrand; Vladimir B. Il’in, Co-Chair (Saint Petersburg State 1963. [3] Sobolev VV. Light scattering in planetary atmospheres. Moscow: University, Russia) Nauka; 1972 (in Russian). English edition: Oxford: Pergamon Press; Alexander F. Kholtygin, Co-Chair (Saint Petersburg State 1975. University, Russia) [4] Sobolev VV. Course in theoretical astrophysics. Moscow: Nauka; 1967 (in Russian). English edition: NASA technical translation TT F-531. Maria V. Kostina, Secretary (Saint Petersburg State Washington, DC: National Aeronautics and Space Administration; University, Russia) 1969. Yulia V. Milanova (Saint Petersburg State University, Russia) Ilya S. Potravnov (Pulkovo Observatory, Russia) Marina S. Prokopjeva (Saint Petersburg State University, Russia) Special Issue Editors Vladimir M. Serbin (Balta Ltd, Russia) Alexander F. Kholtygin Stanislav I. Shirokov (Saint Petersburg State University, Chair of Astronomy, Saint Petersburg State University, 28 Russia) Universiteski Prospect, Saint-Petersburg, 198504, Russia Natalia Y. Sotnikova (Saint Petersburg State University, E-mail address: [email protected] Russia) Olga A. Tsiopa (Pulkovo Observatory, Russia)

Michael I. Mishchenko Acknowledgments NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025, USA We thank all contributors to this special issue for sub- E-mail address: [email protected] mitting state-of-the-art invited reviews and original papers. We also appreciate the time and expertise gener- Received 21 April 2016; accepted 22 April 2016 ously contributed by many reviewers, often on very short notice. José Stoop of Elsevier is recognized for supporting Available online 27 April 2016 the idea of this topical issue. Substantial support of the Sobolev conference was provided by the Saint Petersburg State University (Russia)