We present Mg isotope ratios in 4 red giants of the globular cluster M 13 and 1 red giant of the globular cluster M 71 based on high resolution, high signalto-noise ratio spectra obtained with HDS on the Subaru Telescope. We confirm earlier results by Shetrone that for M 13, the ratio varies from 25+26 Mg / 24 Mg ≃ 1 in stars with the highest Al abundance to 25+26 Mg / 24 Mg ≃ 0.2 in stars with the lowest Al abundance. However, we separate the contributions of all three isotopes and find a considerable spread in the ratio 24 Mg: 25 Mg: 26 Mg with values ranging from 48:13:39 to 78:11:11. As in NGC 6752, we find a positive correlation between 26 Mg and Al, an anticorrelation between 24 Mg and Al, and no correlation between 25 Mg and Al. In M 71, our one star has a Mg isotope ratio 70:13:17
To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.