Astron. Astrophys. 343, 241-250 (1999)

Dynamics of the circumstellar envelope of RT Virginis on the basis of the H₂O maser monitoring

E.E. Lekht ¹, J.E. Mendoza-Torres ¹, M.I. Pashchenko ² and I.I. Berulis <sup>3,4

1</sup> Instituto Nacional de Astrofísica, Óptica y Electrónica, Luis Enrique Erro No. 1, Apdo Postal 51 y 216, 72840 Tonantzintla, Puebla, México
² Sternberg Astronomical Institute, 13 Universitetskij prospekt, 119899 Moscow, Russia
³ Pushchino Radio Astronomy Observatory, Astrospace Centre, Lebedev Institute of Physics, Russian Academy of Sciences, 142292 Pushchino, Russia
⁴ Technological University, Kaunas, Lithuania

Received 27 May 1998 / Accepted 3 November 1998

Abstract

This paper continues the earlier work (Mendoza-Torres et al. 1997) on single-dish 22-GHz observations of the H₂O maser associated with the semiregular variable (SRb-type) RT Vir. New spectra, obtained in 1996-1998, are presented, and an analysis of the emission of individual spectral features during the interval of 1986-1998 is performed. All the observations have been carried out on the RT-22 radio telescope of the Pushchino Radio Astronomy Observatory, Lebedev Institute of Physics, Russian Academy of Sciences. As a result of long-term monitoring, the character of variability of multiple spectral components was traced in detail. For many features, a drift in radial velocity was found. There are time intervals with preferential drift direction of the majority of the spectral features. This trend was the most pronounced at velocities 15.5 km s^-1. Possible causes of the drift observed are discussed. From a superposition of all the spectra and from the mean spectrum for 1984-1998, stellar velocity was determined. It is estimated as  km s^-1. The time interval from March to June 1998 is considered as the period of maximum activity of the H₂O maser RT Vir during the entire timespan of its observations.

Key words: masers stars: circumstellar matter stars: individual: RT Vir radio lines: stars

Send offprint requests to: J.E. Mendoza-Torres

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Contents

• 1. Introduction
• 2. Observations and data reduction
  • 2.1. Observations
  • 2.2. Data reduction
• 3. Presentation of the data
  • 3.1. Three-dimensional data presentation
  • 3.2. Gaussian fitting
  • 3.3. Components of the first group
  • 3.4. Components of the second group
  • 3.5. Components of the third group
  • 3.6. Superposition of all the spectra and the average spectrum
• 4. Discussion
  • 4.1. The structure of the H₂O spectrum and the stellar velocity
  • 4.2. The evolution of the features of the first group
  • 4.3. The evolution of the features of the third group
  • 4.4. The flare of the H₂O maser in 1998
  • 4.5. Variability of the radial velocities of the components
• 5. Conclusions
• Acknowledgements
• References

© European Southern Observatory (ESO) 1999

Online publication: March 1, 1999
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