The chemical composition of Algol systems. V: Confirmation of carbon deficiencies in the primaries of eight systems

We use low-noise CCD spectra of the 4267-A C II line in the spectra of eight Algol-type eclipsing binaries to measure the C abundances of their primaries. A differential LTE analysis of the Algol binaries with respect to single standard stars of the same spectral type shows marginal, to moderate deficiencies of C in the primaries of the binaries. We find [C/H] abundances of −0.62 for U CrB, −0.34 for u Her, ≤+0.24 for δ Lib, −0.22 for β Per, −0.18 for U Sge, −0.48 for λ Tau, −0.35 for TX UMa and −0.16 for RS Vul with respect to the average C abundance of single B-type standard stars. These results confirm those of Cugier and Hardorp, who have used IUE observations of the 1300-A C II lines to determine C abundances in the same stars