An Evolutionary Model for $\beta$ Lyrae

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Session 22 -- Late-Type and Variable Stars
Oral presentation, Monday, 2:30-4:00, Dwinelle 145 Room

[22.08] An Evolutionary Model for $\beta$ Lyrae

A.P.Linnell (Mich.State U.), J.P.DeGreve (NFWO,Belgium)

We have calculated an evolutionary model for $\beta$ Lyrae that matches current model constraints found by Harmanec (1990, AA 237, 91) and Hubeny and Plavec (1991, AJ 102, 1156). The initial component masses were $11.0M_{\sun}$ and $7.35M_{\sun}$. The evolution has been conservative, and the system is approaching the end of mass transfer. Adopting the current mass of the loser as $4.25M_{\sun}$, we find that component will lose an additional $1.0M_{\sun}$ during continuation of the present slow phase of mass transfer. We find a current mass transfer rate of $3 10^{-5}M_{\sun}$ $yr^{-1}$ , in good agreement with the Hubeny and Plavec results of $10^{-4}M_{\sun}$$yr^{-1}$ from entirely different considerations. The evolutionary model predicts a current system luminosity in excellent agreement with the Hubeny and Plavec value for the sum of a main sequence $14.1M_{\sun}$ gainer and an accretion disk. The one-dimensional evolution code overestimates the radius of the gainer. This is a reasonable result in the absence of an explicit evolutionary accretion disk model. APL received partial support from NSF.

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