Progress on a model for β Lyrae

Abstract

It is generally accepted that β Lyrae is a massive mass-transfer system in which the more massive gainer is embedded in a thick accretion disc. No detailed, quantitative accretion disc model of the system, which fits both the available photometric and spectroscopic data, has been published. This paper considers a thick accretion disc model. An empirical two-temperature model for the accretion disc rim produces an accurate fit to the UBV and OAO2 photometry. The two-temperature rim model leads to synthetic spectra with a much larger Balmer jump than is present in spectrophotometric scans. The same model fails to produce IR light curves with the 0.5p eclipse deeper than the 0.0p eclipse, as shown in the observations of Jameson & Longmore. The paper next reports initial results for a model in which an extra source of continuum radiation arises from Thomson scattering of radiation from the gainer, which is hidden from the observer by the thick accretion disc. The adopted rate of mass transfer cannot supply the energy radiated by the accretion disc rim, nor can any credible larger rate. The most likely energy source is the mass gainer.