An Improved Photometric Analysis of SX Aurigae

Abstract

The photometric analysis reported leads to four principal conclusions: 1. The SX Aur system consists of two normal main-sequence stars. The components are very close to the inner Roche limiting surface. 2. The primary component is extremely close to contact with its inner Roche lobe, as well as can be judged from the photometric solution. It is indicated that mass flow from the primary to the secondary has not yet begun. 3. Allowing the bolometric albedo of the secondary component to be a free parameter produces a solution with an excellent fit to the B, V data. The derived value is A₂ = 0.40. This value disagrees with the theoretical value, 1.0, appropriate to radiative atmospheres, and accords with the value appropriate to convective equilibrium. 4. The failure of the parameter set to produce a U fit as good as the B, V fit likely arises from the location of the Balmer discontinuity in the U band, together with the major departure of the radiation curve from the blackbody approximation adopted by the light synthesis program.