Volume 395, Number 1, November III 2002
|Page(s)||77 - 83|
|Section||Interstellar and circumstellar matter|
|Published online||29 October 2002|
The surface carbon and nitrogen abundances in models of ultra metal-poor stars
Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead CH41 1LD, UK
2 INAF – Osservatorio Astronomico Collurania, via Mentore Maggini, 64100 Teramo, Italy
3 Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching, Germany
Corresponding author: H. Schlattl, email@example.com
Accepted: 28 May 2002
We investigate whether the observed high number of carbon- and nitrogen-enhanced extremely metal-poor stars could be explained by peculiar evolutionary properties during the core He flash at the tip of the red giant branch. For this purpose we compute a series of detailed stellar models expanding upon our previous work; in particular, we investigate if during the major He flash the penetration of the helium convective zone into the overlying hydrogen-rich layers can produce carbon- and nitrogen-rich abundances in agreement with current spectroscopic observations. The dependence of this phenomenon on selected model input parameters, such as initial metallicity and treatment of convection is examined in detail.
Key words: stars: abundances / stars: evolution / stars: interiors / stars: late type
© ESO, 2002
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