Accretion on Non-Degenerate Binary Components

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Session 45 -- Early Type Stars
Display presentation, Wednesday, 9:20-6:30, Heller Lounge Room

[45.05] Accretion on Non-Degenerate Binary Components

M.J. Plavec (UCLA), I. Hubeny (USRA)

We are studying accretion disks in a variety of binary systems with non-degenerate components. Disks are modeled by program TLUSDISK, their detailed spectra are calculated for a range of inclination angles, and differential Doppler broadening due to the Keplerian rotation in the disk is duly included. Model spectra are compared with observed IUE and CCD optical spectra. We find that various combinations of the rate of mass transfer, mass and size of the gainer, and degree of viscosity in the disk can produce a wide variety of observable phenomena. Here we report on two cases.\\ (1) The Algol-type eclipsing binary RY Persei with a relatively large gainer mass and low mass transfer rate shows a primary spectrum of B6 IV but with deep and strong UV circumstellar absorptions, corresponding to strong emissions seen during total eclipse. These lines are obviously formed in a layer or column associated with the boundary layer between the disk and the star.\\ (2) The question if a symbiotic spectrum can be produced by an accretion disk around a small red dwarf is studied (case of CI Cygni). The vertical thickness of the disk strongly depends on the Reynolds number describing viscosity, and can be substantial for a conventional value of Re=5000. Since observations of this eclipsing system suggest $i = 73^\circ$, Re would have to be much smaller (1000). This provides an interesting constraint on Re which may be exploited in future studies of disk viscosity.\\ Our models predict the spectra of the various types of binary systems if viewed at moderate or low inclinations, thus offering hints for systematic searches.

Wednesday program listing