THE NATURE OF THE DOPPLER-SHIFT RESIDUALS AND SOME PECULIAR PHENOMENA OF SS-433

Spectroscopic observations in the optical region of the peculiar variable object SS 433 were carried out in the years from 1987 to 1992. The behavior of the moving emission lines of H I and He I basically agrees with those predicted from a combination of the precessional and the nodding motions with periods of 163 days and 6 days, respectively. Thus the so-called dynamic model has been efficient. Part of the residuals of the Doppler shifts may be due to variations in the outflow velocity of the jets. In particular, the residuals with absolute values less than 3000 km s-1 can be well explained as a result of such outflow velocity variations. On the other hand, there should be also other instabilities which lead to larger residuals. A fragmentation of the moving line of Halpha was observed on 1991 October 2. This phenomenon might have been due to an ejection of clouds with unusually high density. Large residuals of the Doppler shifts were observed during 1991 November to 1992 February. The moving emission lines disappeared in 1991 December and in the later half of 1992 February. When the moving lines appeared again in 1992 March, such large residuals were not found. The system of SS 433 seems to have been in an unstable stage in the time from 1991 October to 1992 February.