Rotation statistics of Algol-type binaries and results on RY Geminorum, RW Monocerotis, and RW Tauri

Abstract

Rotation rates and other parameters are estimated from light curves of three Algol-type binaries, and rotation statistics based on both spectral line broadening and light curves are collected for 36 Algol systems. The statistics suggest that a subset of Algols have primary stars which rotate at the centrifugal limit and that many Algols have sufficient continual mass transfer to maintain nonsynchronous rotation. A formal procedure for estimating the critical rotation rate (centrifugal limit) is described. It is found that RY Gem rotates about 14 times faster than synchronously, but not close to its centrifugal limit of about 24 times. For RW Mon, the rotation is about five times synchronous. For RW Tau it was not possible to estimate the rotation from the light curves, but consistency with a published result from line broadening is found.