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On the asymptotic giant branch star origin of peculiar spinel grain OC2
M. Lugaro, A. I. Karakas, L. R. Nittler +4
Microscopic presolar grains extracted from primitive meteorites have extremely anomalous isotopic compositions revealing the stellar origin of these grains. The composition of pres…
The Chemical Evolution of Helium in Globular Clusters: Implications for the Self-Pollution Scenario
Amanda Karakas, Yeshe Fenner, Alison Sills +2
We investigate the suggestion that there are stellar populations in some globular clusters with enhanced helium (Y from 0.28 to 0.40) compared to the primordial value. We assume th…
Helium enhancements in globular cluster stars from Asymptotic Giant Branch star pollution
Amanda Karakas, Yeshe Fenner, Alison Sills +2
Using a chemical evolution model we investigate the intriguing suggestion that there are populations of stars in some globular clusters (e.g. NGC 2808, omega Centauri) with enhance…
The Uncertainties in the 22Ne + alpha-capture Reaction Rates and the Production of the Heavy Magnesium Isotopes in Asymptotic Giant Branch Stars of Intermediate Mass
A. Karakas, M. Lugaro, M. Wiescher +2
We present new rates for the 22Ne(alpha, n)25Mg and 22Ne(alpha,gamma)26Mg reactions, with uncertainties that have been considerably reduced compared to previous estimates, and we s…