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Session 103 - Cool Stars.
Display session, Thursday, January 18
North Banquet Hall, Convention Center

[103.13] Mg Isotope Ratios in the Globular Cluster M13

M. D. Shetrone (UC Santa Cruz)

Seven M13 red giants (Shetrone 1995) are reobserved at high resolution (R=61000) with S/N ranging between 106 to 166 per resolution element at 5135ÅIsotopic analysis of the 5135ÅMgH bands reveal five stars with super solar ratios of ^25Mg + ^26Mg compared with ^24Mg and one star with solar isotopic ratios. Only one star, L598, has sub-solar isotope ratios consistent with those found in other population II stars. The isotope ratios (^25Mg + ^26Mg)/^24Mg anti-correlate with the Al abundances and correlate with the total Mg (^24Mg + ^25Mg + ^26Mg) abundances. The star to star [Mg/Fe] variations are mostly due to ^24Mg, which is inconsistent with the deep mixing scenario of Langer and Hoffman 1996, unless the nuclear cross-sections for proton capture on ^24Mg are larger than currently reported.

Program listing for Thursday