THE NEAR-CONTACT BINARY-SYSTEM RU URSAE MINORIS

A new spectroscopic orbit for both components of the short-period ecli psing binary system RU UMi (P=0.5d) is combined with an accurate R-ban d light-curve to show that the system has a semi-detached configuratio n and may well be in the process of approaching contact for the first time, as previously suspected. This preliminary solution, which includ es corrections to measured velocities for non-Keplerian effects, sugge sts the presence of large-scale spot activity concentrated on the aver ted hemisphere of the secondary component.