Nucleosynthesis in AGB Stars
نویسندگان
چکیده
منابع مشابه
Post-AGB stars as testbeds of nucleosynthesis in AGB stars
We construct a data base of 125 post-AGB objects (including R CrB and extreme helium stars) with published photospheric parameters (effective temperature and gravity) and chemical composition. We estimate the masses of the postAGB stars by comparing their position in the (log Teff , log g) plane with theoretical evolutionary tracks of different masses. We construct various diagrams, with the ai...
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We present detailed abundance results concerning CEMP (Carbon Enhanced Metal-Poor) stars and the various subclasses. Statistical arguments from radial velocity monitoring show that these stars are all binaries and have mass transferred from a former AGB. Therefore these stars are the direct witnesses of the nucleosynthesis production of the first low and intermediate mass stars. To put CEMP sta...
متن کاملNucleosynthesis in Intermediate Mass Agb Stars
We present a summary of the main sites for nucleosynthesis in intermediate mass Asymptotic Giant Branch (AGB) stars. We then discuss some detailed evolutionary models and how these have been used to create a synthetic evolution code which calculates the nucleosynthesis very rapidly, enabling us to investigate changes in some uncertain parameters in AGB evolution, such as mass-loss and dredge-up...
متن کاملNeutron-capture nucleosynthesis in AGB stars
Recent AGB models including diffusive overshoot or rotational effects suggest the partial mixing (PM) of protons from the H-rich envelope into the C-rich layers during the third dredge-up. In order to study the impact of such a mixing on the surface abundances, nucleosynthesis calculations based on stellar AGB models are performed for different assumptions of protons (ranging from Xmix p = 10 −...
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We have discovered lines of highly ionized fluorine (F and F ) in the far-UV spectra of extremely hot (Teff=85 000–150 000 K) post-AGB stars. Our sample comprises H-rich central stars of planetary nebulae as well as H-deficient PG1159 stars. We performed non-LTE calculations and find strong F overabundances (up to 10−4 by mass, i.e., 250 times solar) in a number of PG1159 stars, while F is ...
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 1999
ISSN: 0074-1809
DOI: 10.1017/s0074180900202854