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Paper: MG and AL Abundances in Halo Globular Clusters
Volume: 92, Formation of the Galactic Halo. . . . Inside and Out
Page: 383
Authors: Shetrone, Matthew D.
Abstract: Results of a systematic survey of Al and Mg abundances in globular cluster giants are reported. Star to star variations in Al abundances for bright giants in M92 ([Fe/H] = -2.2), M13 ([Fe/H] = -1.5) and M5 ([Fe/H]= -1.2) have been detected. The Al to Na correlation and the Al to O anti-correlation are consistent with the predictions of the deep mixing theory (Langer & Hoffman 1996). Mg abundances were obtained independently from spectral synthesis of the 5136 Angstroms MgH features and from EW analysis of five Mg I features. A comparison of the two sets of Mg abundances shows good agreement. M13, which has the largest spread in Al, Na and O abundances, has star-to-star variations in the Mg abundance that are anti-correlated with Al. The [Al/Mg] ratio is consistent with the hypothesis that Mg is being processed into Al. However, since only (25) Mg and (26) Mg are expected to be converted to (27) Al, the implied isotopic ratio for Mg would be extremely non-solar.
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