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Molecular Masers in Variable Stars

Published online by Cambridge University Press:  05 March 2013

Georgij M. Rudnitskij
Georgij M. Rudnitskij*
Affiliation:
Sternberg Astronomical Institute*, 13 Universitetskij prospekt, Moscow, 119899 Russia; gmr@sai.msu.ru
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Abstract

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When a star with a mass of one to a few solar masses enters the red giant stage of its evolution, the radius of its atmosphere reaches several astronomical units. Pulsational instability is typical for this stage. Most stars become Mira-type or semiregular variables with light cycles of a few hundred days. Red giants lose mass at a rate M = 10−7−10−5M⊙ yr−1. Extensive gas–dust circumstellar envelopes form. These envelopes contain various molecular species. Some of these molecules (OH, H2O, SiO, HCN) manifest themselves in maser radio emission. Data on the H2O maser variability and its connection with the stellar brightness variations are discussed. In the H2O line circumstellar masers can be divided into ‘stable’ (showing persistent emission — R Aql, U Her, S CrB, X Hya) and ‘transient’ (appearing in the H2O line once per 10–15 stellar light cycles — R Leo, R Cas, U Aur). Physical mechanisms of the maser variability are discussed. The most probable process explaining the observed visual–H2O correlation is the influence of shock waves on the masing region. Usually it is assumed that shocks in Mira atmospheres are driven by stellar pulsations. Here an alternative explanation is proposed. If a star during its main sequence life possessed a planetary system, similar to the solar system, the planets will be embedded in a rather dense and hot medium. Effects of a planet revolving around a red giant at a short distance (inside its circumstellar envelope) are discussed. A shock produced by the supersonic motion of a planet can account for the correlated variability of the Hα line emission and H2O maser. If the planetary orbit is highly eccentric, then the connected Hα–H2O flare episodes may be explained by the periastron passage of the planet. New tasks for the upgraded ATCA are discussed.

Keywords

stars: late-typemasersshock wavesextrasolar planets
Type
Research Article
Information
Publications of the Astronomical Society of Australia , Volume 19 , Issue 4 , 2002 , pp. 499 - 504
Copyright
Copyright © Astronomical Society of Australia 2002

References

Benson, P. J., Little-Marenin, I. R., Woods, T. C., Attridge, J. M., Blais, K. A., Rudolph, D. B., Rubiera, M. E., & Keefe, H. L. 1990, ApJS, 74, 911 CrossRefGoogle Scholar
Berulis, I. I., Lekht, E. E., Pashchenko, M. I., & Rudnitskij, G. M. 1983, SvA, 27, 179 Google Scholar
Bieging, J. J., Shaked, S., & Gensheimer, P. D. 2000, ApJ, 543, 897 CrossRefGoogle Scholar
Castelaz, M. W., & Luttermoser, D. G. 1997, AJ, 114, 1584 Google Scholar
Chapman, J. M., & Rudnitskij, G. M. 2002, PASA, submittedGoogle Scholar
Clayton, M. L., & Feast, M. W. 1969, MNRAS, 146, 411 CrossRefGoogle Scholar
Esipov, V. F., Pashchenko, M. I., Rudnitskij, G. M., & Fomin, S. V. 1999, AstL, 25, 672 Google Scholar
Fox, M. W., & Wood, P. R. 1985, ApJ, 297, 455 Google Scholar
Fox, M. W., Wood, P. R., & Dopita, M. A. 1984, ApJ, 286, 337 Google Scholar
Gillet, D., Maurice, E., & Baade, D. 1983, A&A, 128, 384 Google Scholar
González-Alfonso, E., Cernicharo, J., Alcolea, J., & Orlandi, M. A. 1998, A&A, 334, 1016 Google Scholar
Greene, A. E., & Wing, R. F. 1975, ApJ, 200, 688 CrossRefGoogle Scholar
Habing, H. J. 1996, A&AR, 7, 97 Google Scholar
Haniff, C. A., Scholz, M., & Tuthill, P. G. 1995, MNRAS, 276, 640 Google Scholar
Hinkle, K. H., & Barnes, T. G. 1979, ApJ, 234, 548 Google Scholar
Hinkle, K. H., Scharlach, W. W. G., & Hall, D. N. B. 1984, ApJS, 56, 1 Google Scholar
Knapp, G. R., Phillips, T. G., Leighton, R. B., Lo, K. Y., Wannier, P. G., Wootten, H. A., & Huggins, P. J. 1982, ApJ, 252, 616 Google Scholar
Kholopov, P. N., et al. 1985–1987, General Catalogue of Variable Stars. Vols. I–III (Moscow: Nauka)Google Scholar
Lekht, E. E., Mendoza-Torres, J. E., Rudnitskij, G. M., & Tolmachev, A. M. 2001, A&A, 376, 928 Google Scholar
Little-Marenin, I. R., Benson, P. J., & Dickinson, D. F. 1988, ApJ, 330, 828 Google Scholar
Lucas, R., Omont, A., & Guilloteau, S. 1988, A&A, 194, 230 Google Scholar
Menten, K. M., & Melnick, G. J. 1991, ApJ, 377, 647 Google Scholar
Olofsson, H., Lindqvist, M., Nyman, L.-Â., & Winnberg, A. 1998, A&A, 329, 1059 Google Scholar
Plambeck, R. L., Wright, M. C. H., & Carlstrom, J. E. 1990, ApJ, 348, L65 Google Scholar
Reid, M. J., & Menten, K. M. 1997, ApJ, 476, 327 Google Scholar
Rudnitskij, G. M., & Chuprikov, A. A. 1990, SvA, 34, 147 Google Scholar
Rudnitskij, G. M., Lekht, E. E., Mendoza-Torres, J. E., Pashchenko, M. I., & Berulis, I. I. 2000, A&AS, 146, 385 Google Scholar
Rybicki, K. R., & Denis, C. 2001, Icarus, 151, 130 Google Scholar
Soker, N. 1999, MNRAS, 306, 806 Google Scholar
Soker, N. 2000, A&A, 357, 557 Google Scholar
Struck-Marcell, C. 1988, ApJ, 330, 986 Google Scholar
Taam, R. E., Bodenheimer, P., & Ostriker, J. P. 1978, ApJ, 222, 269 Google Scholar
Tsikulin, M. A. 1969, Shock Waves Induced in the Atmosphere by Motion of Large Meteoritic Bodies (Moscow: Nauka) (in Russian)Google Scholar
Udry, S., Jorissen, A., Mayor, M., & Van Eck, S. 1998, A&AS, 131, 25 Google Scholar
Wood, P. R. 1979, ApJ, 227, 220 Google Scholar
Yates, J. A., Cohen, R. J., & Hills, R. E. 1995, MNRAS, 273, 529 Google Scholar