M SINGH, M MON, T KOGURE, M SUZUKI
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 46(1) 27-43 1994年 査読有り
Based on a series of Coude spectra taken with the 188-cm reflector of the Okayama Astrophysical Observatory over an interval of 18 yr, the spectroscopic behavior in the Balmer and He I lambda3888 lines of the binary Be star phi Per (orbital period of 126.696 d) is presented. We have confirmed the following phenomena: (1) the V/R ratio (intensity ratio of violet to red peaks of the double-peaked emission lines) varies synchronously with the binary phase, and its amplitude is about 2; (2) the shell absorption lines become very strong at a phase of around 0.1; (3) there is a remarkable hump in the radial velocity curve of the shell lines near to phases of 0.4 to 0.6; and (4) the peak separations of the emission lines do not vary with the phase, but remain constant.
It seems difficult to represent the phi Per phenomena sited above with the simple envelope models which have so far been adopted for many Be stars. The difficulties are pointed out for the axisymmetric rotating-pulsating envelope model and the elliptic disk model with apsidal motion. The formation of a high-density region around the primary is required for the appearance of a strong shell at a particular phase. The hump in the radial-velocity curves requires that the envelope around the primary should be elongated perpendicular to the binary axis. Using the peak separations of the Balmer emission lines, a large extension of the envelope which overflows the Roche lobe of the primary was estimated. This infers that an envelope really extends beyond the Roche lobe and thus may be a very complicated one, or that the binary parameters so far adopted (20 M. and 4 M.) are not reliable. The possibility of less massive binary parameters is suggested.