Flare activity of the long-period variable star R Leonis

Results of the observations of the Mira Ceti-type variable star R Leo carri ed out in 1994-1999 are presented. Optical spectra of the star and profiles of the 1.35-cm water-vapor maser line were obtained. The star underwent a strong flare of the Ha emission line in May-June 1996. By the end of 1997 t he star flared in the H2O maser line to a flux density of about 140 Jy. In 1983-1997 the H2O emission of R Leo did not exceed the sensitivity level of < 10 Jy, and after the flare, in June 1998, it again fell below 10 Jy. Bot h flares (H alpha and H2O) took place when the star was near its minimum vi sual brightness. The sequence of the flares can be explained by the impact of a shock wave on the inner layers of the circumstellar envelope of R Leo.