H-alpha observations of RS Canum Venaticorum stars. II - 1981 observations for UX Arietis, HR 1099, and BD +61 deg 1211

Abstract

H-alpha line observations made during 1981 of the highly active RS CVn stars UX Ari, HR 1099, and BD +61 deg 1211 are presented and discussed. Excess H-alpha emission profiles derived by subtracting synthesized comparison-star spectra are analyzed to find that the UX Ari and HR 1099 systems differ significantly in the strength of the excess emission from their secondaries. Specifically, it is found that in UX Ari the H-alpha emission of the K subgiant completely dominates that of the G V secondary. In HR 1099, however, the K1 IV primary is responsible for 86 percent of the total emission and the G5 IV secondary 14 percent, with the smaller secondary showing the higher surface flux. H-alpha spectra from the single-lined system BD +61 deg 1211 show a strong, broad emission line which is variable by over a factor of 3 during the observational period. The data for these systems are discussed in terms of the L(H-alpha)/L(bol) vs log P relation for the RS CVn stars.