JET-LIKE STRUCTURES IN BETA-LYRAE - RESULTS OF OPTICAL INTERFEROMETRY, SPECTROSCOPY AND PHOTOMETRY

A preliminary analysis of an extensive collection of interferometric, spectroscopic and photometric observations of the bright Be star beta Lyr lead to the following main conclusions: (1) The bulk of the H alph a and He I 6678 emission seems to originate in jets of material perpen dicular to the orbital plane of the binary. The jets are associated wi th the more massive component of the binary (star 1) and probably eman ate from the 'hot spot' in the disk, i.e. the region of interaction of the gas stream flowing from the Roche-lobe filling B6-8II component ( star 2) toward star 1. Some contribution to the emission also comes fr om a region located between the two stars (the gas stream and the 'hot spot') and from the 'pseudoatmosphere' of the accretion disk around s tar 1. (2) The 282-d cyclic variation of the light curve of beta Lyr i s confirmed on the basis of 2852 homogenized V-band observations cover ing an interval of 36 yrs. We find, however, that the amplitude and ph ase of these variations vary with the orbital phase: the long-term mod ulation of the light curve almost disappears near orbital phases O-P.2 5 and O-P.50 (elongation and secondary eclipse). (3) Pronounced line-p rofile variations of the H alpha and He I 6678 lines on a time scale s horter than one orbital period were clearly detected. They may be peri odic, with a period near 4.(d)70 - 4.(d)75, and this periodicity may b e related to the 282-d change via the orbital period.