In:
Proceedings of the International Astronomical Union, Cambridge University Press (CUP), Vol. 5, No. S268 ( 2009-11), p. 405-410
Abstract:
We examine the effects of thermohaline mixing on the composition of the envelopes of low-metallicity asymptotic giant branch (AGB) stars. We have evolved models of 1, 1.5 and 2M ⊙ and of metallicity Z = 10 −4 from the pre-main sequence to the end of the thermal pulsing asymptotic giant branch with thermohaline mixing applied throughout the simulations. We find that the small amount of 3 He that remains after the first giant branch is enough to drive thermohaline mixing on the AGB and that the mixing is most efficient in the early thermal pulses, with the efficiency dropping from pulse to pulse. We note a surprising increase in the 7 Li abundance, with log 10 ϵ( 7 Li) reaching values of over 2.5 in the 1.5M ⊙ model. It is thus possible to get stars which are both C- and Li-rich at the same time. We compare our models to measurements of carbon and lithium in carbon-enhanced metal-poor stars which have not yet reached the giant branch. These models can simultaneously reproduced the observed C and Li abundances of carbon-enhanced metal-poor turn-off stars that are Li-rich.
Type of Medium:
Online Resource
ISSN:
1743-9213
,
1743-9221
DOI:
10.1017/S1743921310004539
Language:
English
Publisher:
Cambridge University Press (CUP)
Publication Date:
2009
detail.hit.zdb_id:
2170724-8
SSG:
16,12
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