The Brightest Carbon Stars
نویسندگان
چکیده
It is currently accepted that Hot-Bottom-Burning (HBB) in intermediate-mass asymptotic giant branch (AGB) stars prevents the formation of C stars. Nevertheless, we present the results of some detailed evolutionary calculations which show that even with HBB we obtain C stars at the highest luminosities reached on the AGB. This is due to mass-loss reducing the envelope mass so that HBB ceases but dredge-up continues. The high mass-loss rate produces an optically thick wind before the star reaches C/O> 1. This is consistent with the recent results of van Loon et al. (1997a,b) who find obscured C stars in the Magellanic Clouds at luminosities up to Mbol = 6:8.
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