Carbon abundance in the primaries of six Algol-type stars.

Abstract

The abundance analysis of carbon in six Algol-type stars was performed using IUE archival data. In order to interpret the observed spectra, both LTE and non-LTE line profiles are computed. A cosmic abundance of carbon is obtained, log N(C/H) = - 3.48, in the primary components of Delta Librae, U Sagittae, RS Vulpeculae and u Herculis. All these systems have mass ratios q greater than 0.32. In TX Ursae Majoris, log N(C/H) = - 3.73 + or - 0.20 is obtained, whereas in U Coronae Borealis (q = 0.29), log N(C/H) = - 3.89 + or - 0.20 is obtained. The result is discussed in terms of the evolutionary status of Algol-type stars.