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Astron. Astrophys. 332, L17-L20 (1998)

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Letter to the Editor

The brightest carbon stars

C.A. Frost 1, 2, R.C. Cannon 1, 3, J.C. Lattanzio 1, 2, 4, P.R. Wood 5 and M. Forestini 4

1 Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA, UK
2 Department of Mathematics, Monash University, Clayton, Victoria, 3168, Australia
3 Department of Physiology and Pharmacology, School of Biological Sciences, University of Southampton, SO16 7PX, UK
4 Laboratoire d'Astrophysique, Observatoire de Grenoble, Université Joseph Fourier, B.P. 53, F-38041 Grenoble Cedex 9, France
5 Mount Stromlo and Siding Spring Observatories, The Australian National University, Private Bag, Weston Creek P.O., A.C.T. 2611, Australia

Received 5 August 1997 / Accepted 11 September 1997


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 [FORMULA]. 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 [FORMULA].

Key words: stars: AGB – stars: Carbon stars – stars: Nucleosynthesis

Send offprint requests to: J. Lattanzio, Department of Mathematics, Monash University, Clayton, Victoria, 3168, Australia


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© European Southern Observatory (ESO) 1998

Online publication: March 10, 1998