Polarization measurement and study of thirty RS CVn stars

Abstract

We made polarization measurement on 30 RS CVn systems using the Berger polarimeter of McDonald Observatory in July-December 1984, of which 26 systems were measured for the first time. The results are given here. They show that for most RS CVn systems, the optical linear polarization is weak, generally below 0.45%, averaging about 0.20%. Some systems, like AR Lac, HR 5110, HD 8357, HK Lac, HR 7275 and HR 7428 have polarization above 0.03%, which showed time variations by factors between 10 and 30. For HD 8357 and ER Vul, there is a clear connection between the polarization and the orbital phase.