NOAO > Observing Info > Approved Programs > 2009B-0083
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NOAO > Observing Info > Approved Programs > 2009B-0083 |
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PI: Thomas Lebzelter, University of Vienna, lebzelter@astro.univie.ac.at
Address: Department of Astronomy, Tuerkenschanzstrasse 17, Vienna A1180, Austria
CoI: Kenneth Hinkle, NOAO
CoI: Oscar Straniero, INAF Teramo
CoI: Michael Lederer, University of Vienna
Title: A taste of the interior: oxygen abundances in cluster red giants
Abstract:
In our current understanding fo stellar evolution mixing processes
play a key role. The mixing processes also are a critical step in the
cosmic matter cycle. The surface abundance of stars is modified by a
series of mixing events during the advanced stages of stellar evolution.
This can be studied best by measurements in cluster AGB stars. Many
aspects of the mixing are not yet fully understood. Here we want to
focus on understanding the role of non-convective (`extra') mixing. We
propose to observe the isotopic ratios of oxygen, which are expected to
be very sensitive to the depth reached by the mixing events, in a sample
of AGB stars from the cluster 47 Tuc. While third dredge up should not
occur due to the low mass of these stars, extra-mixing is expected to
have affected the surface abundances both during the RGB and AGB phase.
Furthermore, our studies will provide a highly needed data point at the
low mass end for testing the predicted relation between mass and
isotopic ratios.
National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360
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NOAO > Observing Info > Approved Programs > 2009B-0083 |
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