Astron. Astrophys. 319, 511-514 (1997)

Faint carbon stars from the evolution of close binaries

Ju. Frantsman

Radioastrophysical observatory, Latvian Academy of Sciences, Akademijas laukums 1, LV-1527, Riga, Latvia

Received 21 March 1996 / Accepted 17 July 1996

Abstract

The assumption that faint carbon stars in the Magellanic Clouds are on the early asymptotic giant branch (E-AGB) evolutionary stage, is examined using population simulation techniques. It is assumed that these stars are formed as a result of the mass transfer in close binary systems while the primary is a carbon star on the thermally-pulsing AGB (TP-AGB) stage. The populations of carbon stars resulting from both single-star evolution and mass transfer in close binary systems have been calculated. For the heavy element abundance by mass , the expected amount of E-AGB carbon stars is comparable with the amount of those in the TP-AGB stage. The theoretically obtained and observed luminosity functions of E-AGB carbon stars are similar. Examples illustrating the importance of correct identification of star's evolutionary stage for the interpretation of observations are given. The ignorance of the fact that AGB consists of two stages of the evolution leads to wrong cluster ages resulting from the luminosities of AGB stars.

Key words: stars: carbon stars: evolution stars: AGB Magellanic Clouds stars: binaries: close

Online publication: July 3, 1998

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