The chemical compositions of Algol systems - V. Confirmation of carbon deficiencies in the primaries of eight systems.
Abstract
We use low-noise CCD spectra of 4267-Å 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-Å C II lines to determine C abundances in the same stars. The C deficiencies are a consequence of a previous episode of mass transfer in which the secondary, which was initially the more massive star, has transferred C-deficient, CNO-cycle processed material to the primary. A comparison of observed and theoretical abundances suggests that the mass transfer cannot have been extremely non-conservative, although it may have been mildly so.
- Publication:
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Monthly Notices of the Royal Astronomical Society
- Pub Date:
- December 1993
- DOI:
- 10.1093/mnras/265.3.581
- Bibcode:
- 1993MNRAS.265..581T
- Keywords:
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- stars: abundances - stars: atmospheres - binaries: eclipsing - stars: massloss