A Photometric study of the near-contact system RU Ursae Minoris

The near-contact system RU UMi with an F0 primary and a K5 secondary was observed in U, B and V wavelengths in May and July 1998, as well as in March, May and July 1999. Six new observed times of minima are given and a new ephemeris is proposed. The basic parameters of the system extracted by our observations were used for spot modelling of the light curves. A simple spot distribution was determined, based on a model with one relatively small cool spot on the surface of the secondary. Absolute elements were calculated and the evolutionary status was determined. Our data favor a semi-detached configuration, with the secondary filling its inner Roche lobe; the primary must also be near the limits of its lobe. Table 2 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strabg.fr(130.79.128.5)} or via http://cdsweb.u-strasbg.fr/cgi-bin/qeat?/A+A/369/960