Jet-like structures in B Lyrae.
A preliminary analysis of an extensive collection of interferometric, spectroscopic and photometric observations of the bright Be star β Lyr lead to the following main conclusions: (1) The bulk of the Hα and He I 6678 emission seems to originate in jets of material perpendicular to the orbital plane of the binary. The jets are associated with the more massive component of the binary (star 1) and probably emanate 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 from a region located between the two stars (the gas stream and the `hot spot') and from the `pseudoatmosphere' of the accretion disk around star 1. (2) The 282-d cyclic variation of the light curve of β Lyr is confirmed on the basis of 2852 homogenized V-band observations covering an interval of 36yrs. We find, however, that the amplitude and phase of these variations vary with the orbital phase: the long-term modulation of the light curve almost disappears near orbital phases 0.25P and 0.50P (elongation and secondary eclipse). (3) Pronounced line-profile variations of the Hα and He I 6678 lines on a time scale shorter than one orbital period were clearly detected. They may be periodic, with a period near 4.70-4.75d, and this periodicity may be related to the 282-d change via the orbital period.
|Main Author:||Harmanec, P.|
|Other Authors:||Morand, F., Bonneau, D., Jiang, Y., Yang, S., Guinan, E. F., Hall, D. S., Mourard, D., Hadrava, P., Bozic, H., Sterken, C., Tallon-Bosc, I., Walker, G. A. H., McCook, G. P., Vakili, F., Stee, Ph., Le Contel, J. M.|