AAS 199th meeting, Washington, DC, January 2002
Session 137. Topics in Stellar Evolution
Display, Thursday, January 10, 2002, 9:20am-4:00pm, Exhibit Hall

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[137.08] The Carbon Isotope Ratio in Giants in the Globular Cluster M3

C. A. Pilachowski (Indiana University), C. Sneden (University of Texas at Austin)

The discovery of Li-rich giants in globular clusters has led to some effort to understand the origin of this phenomenon. Two models have been proposed to explain the presence of Li in low mass giants. In the first, lithium enrichment, as well as rotational spin-up and mass loss, occurs when giants accrete massive planets. The second model invokes extra mixing, known to occur in low mass giants, to transport 7Be from the H-burning shell up to the base of the convective envelope, where it is then transported to the surface. The extra mixing is attributed to the interaction of meridional circulation and rotation-induced turbulence associated with mass-loss. While the first model has no predicted effect on the carbon isotope ratio, the second model forces a reduction in the carbon isotope ratio, pushing the value closer to the equilibrium ratio. Here we report the determination of the carbon isotope ratio in four giants in the globular cluster M3, including the Li-rich giant IV-101. The spectra were obtained using NIRSPEC at the Keck Observatory (through the allocation provided to the International Gemini Observatory) and using Phoenix on NOAO's Mayall 4-m Telescope on Kitt Peak. The carbon isotope ratio in M3's IV-101 is about 10, rather higher than what is found in most other globular cluster giants of similar temperature.

The author(s) of this abstract have provided an email address for comments about the abstract: catyp@astro.indiana.edu

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