1999A&A...343..241L

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 <15.5km/s. 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 V_* was determined. It is estimated as 17.3±0.2km/s. 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.