A Period Study and Light Synthesis for the W Ursae Majoris Type Binary SS Arietis

Abstract

Numerous new CCD measures of the cool overcontact binary SS Arietis are compiled into six well-covered light curves. The confusing history of the binary's period variability is laid out in order to consider the diverse interpretations that have been presented previously. It is concluded that the period activity can be ascribed to no fewer than three separate causes. There is some little support for a magnetic cycle functioning in phase with one of the components of the period variability. The three light curves from 1996 have responded satisfactorily to a modern synthesis code, and the characterization of the binary characterization is better constrained than was the case from earlier light-curve studies. Light curves from 1999 have not been so satisfactorily represented. Conditioning the light-curve results with published radial velocities has very little effect on the light-curve parameters. It does, however, reveal a curious distribution of the velocity residuals, and we offer some possible interpretations. Low-level spot activity is also modeled. There is no evidence of a third star contributing significant light to the system.