Astron. Astrophys. Suppl. Ser. 138, 203-211

New BVR photometry of six prominent RS Canum Venaticorum binaries

Padmakar and S.K. Pandey

Send offprint request: S.K. Pandey

School of Studies in Physics, Pt. Ravishankar Shukla University, Raipur, 492 010, India

Received January 16, 1998; accepted April 16, 1999

Abstract:

A new BVR photometry of six prominent RS CVn stars: V711 Tau, UX Ari, IM Peg, II Peg, $\sigma$ Gem and $\lambda$ And, carried out during 1995-97, is presented. The new results reveal significant evolution in the shape as well as in the amplitude of light curves of these binaries. The traditional two-starspot model has been used to obtain the spot parameters from the observed light curves of the stars. Changes in spot area and their location on stellar surface can be noticed from extracted spot parameters. Some of these stars are found to have significant variation in (B-V) and (V-R) colour indices. The (V-R) colour index variation found in IM Peg, II Peg and $\lambda$ And have been used for determining starspot effective temperatures.

Key words: stars: variables -- stars: binaries: close stars: activity -- stars: chromosphere -- starspots