Third Dredge-up in Globular Cluster AGB Stars: Observation Versus Theory

Autor(en)

Michael Lederer, Thomas Lebzelter, Oscar Straniero, Bernhard Aringer

Abstrakt

The changes in the surface abundances of Asymptotic Giant Branch (AGB) stars are due to ongoing nucleosynthesis in the stellar interior accompanied by strong mixing events. Quantitative details of the mixing mechanism - commonly dubbed Third Dredge-Up (TDU) - are still unclear. We derive the C/O ratio and the carbon isotopic ratio 12C/13C from high-resolution near-infrared spectra of a number of AGB stars in the globular cluster NGC 1846 in the Large Magellanic Cloud (LMC). Our sample is well defined in metallicity and mass which allows us to trace the TDU along the AGB as a function of luminosity. Supplementary, we compare the experimentally derived values to results from stellar evolution models. For these calculations we use a set of newly generated opacity coefficients which properly take into account the carbon (and nitrogen) enhancement caused by the third dredge-up.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

Osservatorio Astronomico di Collurania-Teramo

Seiten

43-50

Anzahl der Seiten

8

Publikationsdatum

2007

ÖFOS 2012

1030 Physik, Astronomie

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/fb7bc7f7-8e78-41af-b4e4-3f27ed24bafb