NOAO >   Observing Info >   Approved Programs >   2013B-0218

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Proposal Information for 2013B-0218


PI: Thomas Lebzelter, University of Vienna, thomas.lebzelter@univie.ac.at
Address: Department of Astronomy, Turkenschanzstrasse 17, Vienna A-1180, Austria

CoI: Kenneth Hinkle, NOAO
CoI: Walter Nowotny, University of Vienna
CoI: B. Aringer, University of Vienna
CoI: O. Straniero, INAF-Osservatorio Astronomico di Collurania

Title: Oxygen isotopes, AGB stars, and pre-solar grains

Abstract: The composition of grains in the pre-solar nebula is determined by mass ejected by stars. The abundance pattern of these dust particles can be used to identify the circumstellar envelopes where they formed. For oxygen in the grains the relative abundances of the isotopes tell us the mass of the star where the oxygen originated. However, the story is a complex one since the surface element abundances of low and intermediate mass stars are modified by a series of mixing events during the advanced stages of stellar evolution. Many aspects of the mixing of the products of stellar interior nuclear synthesis are not yet understood. Currently, the interpretation of the origin of the pre- solar dust grains is primarily based on stellar evolution models. We propose to establish an observational basis by determining oxygen isotopic ratios in a sample of AGB stars of known mass. These ratios are expected to be very sensitive to the depth reached by the mixing events, allowing an independent test of stellar evolution and mixing models.


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NOAO >   Observing Info >   Approved Programs >   2013B-0218

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