A PHOTOMETRIC-STUDY OF THE PECULIAR BINARY STAR V-SAGITTAE

High-speed photometric UBV observations of the novalike variable V Sag ittae conducted during 1994 and 1995 are reported. The data consist of a total of 152 hr of observations, covering the entire 12.3 hr orbita l period. Analysis of the photometry using the new Wilson eclipsing-bi nary code suggests a model where mass is being transferred from a 0.86 M., evolved, helium-burning star, which fills its Roche lobe, to a 3. 48 M. evolved companion. Thirteen new timings of primary eclipse in co njunction with published timings from 1946 to 1996 show that the orbit al period is changing at a rate (P) OVER DOT = -5.1(+/-1.0) x 10(-10). We derive a lower limit to the mass-loss rate from the primary star o f (M) OVER DOT (1) similar to 4.4(+/-0.1) x 10(-7) M. yr(-1). V Sge ap pears to be in a short-lived evolutionary state with a lifetime of sim ilar to 2 x 10(6) yr.