A PHOTOMETRIC ANALYSIS AND SPOT MODEL OF THE DETACHED ECLIPSING BINARY UV LEONIS

Eighteen nights of UBV(RI)(c) photometric data are presented for UV Le onis. Times of minima were determined for nine eclipses. The light cur ve shows distortions that change within weeks. Stellar and spot parame ters were solved by the Wilson synthesis code. Two dark spots modeled on the secondary component were needed to reproduce the light curves. The spotted regions are on average 965 K cooler than the surrounding p hotosphere, and are located at high latitudes. Primary minimum is an o ccultation. UV Leo consists of two solar-type stars with both being sl ightly larger, and more massive than the Sun (M(1)=1.13 M., M(2)=1.09 M., R(1)=1.081 R., R(2)=1.186 R., T-1=5916 K, T-2=5861 K) The adopted spectral types are GO V and G2 V for the primary and (unspotted) secon dary components, respectively. On the HR diagram, the primary componen t lies in the same region as other detached nonemission components of main-sequence binaries; the secondary is similar to the active compone nts of RS CVn systems. The secondary component is proposed to have bee n originally the more massive star. Mass loss has presumably occurred as it began to move towards the Hertzsprung gap. (C) 1996 American Ast ronomical Society.