2010/11/09 by P. Neyskens, S. Van Eck, Neyskens, Pieter +9
Physics and Astronomy · #Astro and Planetary Science #Astronomy and Astrophysical Research #FOS: Physical sciences #Solar and Stellar Astrophysics (astro-ph.SR) #Stellar, planetary, and galactic studies
paper · pdf · doi:10.48550/arxiv.1011.2054
openalex publication_date 2010/11/09 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
During the evolution on the AGB, S-type stars are the first objects to\nexperience s-process nucleosynthesis and third dredge-ups, and therefore to\nexhibit sprocess signatures in their atmospheres. Their significant mass loss\nrates (10-7 to 10-6 M*/year) make them major contributors to the AGB\nnucleosynthesis yields at solar metallicity. Precise abundance determinations\nin S stars are of the utmost importance for constraining e.g. the third\ndredge-up luminosity and efficiency (which has been only crudely parameterized\nin all current nucleosynthetic models so far). Here, dedicated S-star model\natmospheres are used to determine precise abundances of key s-process elements,\nand to set constraints on nucleosynthesis and stellar evolution models. A\nspecial interest is paid to technetium, an element with no stable isotopes\n(99Tc, the only isotope produced by the s-process in AGB stars, has a half-life\nof 2.1 x 105 years). Its detection is considered as the best signature that\nthe star effectively populates the thermally-pulsing AGB phase of evolution.\nThe derived Tc/Zr abundances are compared, as a function of the derived [Zr/Fe]\noverabundances, with AGB stellar model predictions. The [Zr/Fe] overabundances\nare in good agreement with the model predictions, while the Tc/Zr abundances\nare slightly overpredicted. This discrepancy can help to set better constraints\non nucleosynthesis and stellar evolution models of AGB stars.\n