Spectrographic observations of omicron andromedae from 1967 to 1976

The results of qualitative analysis and radial velocity (RV) determinations from 1967 to 1976 are given. These analyses show sometimes the presence of a thin variable shell also in the years 1967–1974, before the appearance of the envelope. Intensity variations of the metallic lines seem to indicate that in the same period changes of temperature and/or electron pressure may occur in the photospheric layers. In the period 1975–76, the considerable range ofRV and the variability of the shell features show that the shell is rather active. Some conspicuousRV variations seem to be correlated to brightness changes. TheRV do not confirm the periods suggested by the photometric observations. A periodogram analysis givesRV curves with a poor evidence of periodicity. However, the periodP=1^d.5845 obtained from this analysis, close to that of Schmidt, seems to confirm Schmidt's hypothesis of a contact binary system. The periodogram analysis of theRV during the years 1900–1976 and some physical arguments, suggest a probable photospheric activity or an invisible companion with the observed shell period of 30 yr. The duplicity, suggested by Kí and Harmanec (1975) for all the Be stars, could be yet questioned foro And.Thesis for the degree of Applied Physics.