论文标题
高温状态中的多个恒星种群：球状簇M 54中的钾丰度（NGC 6715）
Multiple stellar populations in the high-temperature regime: Potassium abundances in the globular cluster M 54 (NGC 6715)
论文作者
论文摘要
在球状簇（GCS）中的多个恒星种群中，非常高温H燃烧的状态（能够产生钾的元素）仍然受到探索很差。在这里，我们介绍了42个NGC 6715巨头（M 54）中K的首次丰度分析，并具有先前在我们的火焰调查中得出的光元素的均匀丰度。由于质量较大和高金属性，该GC可能会预期大量的K，该GC位于Sagittarius Dwarf Galaxy的核中。实际上，我们发现[k/fe]跨越约1个DEX，[K/fe]呈现出显着的反相关性，而[O/Fe]比率有显着的反相关性，而不管M 54中的金属性成分如何。k-mg抗可相关的证据也存在，但这在统计上是统计的，因为缺乏MG-Poor的明星，因此这是统计上的Marginal。但是，我们发现K和Ca之间存在很强的相关性。这些观察结果清楚地表明，M 54中的K增强可能是由于相同的核反应网络引起了多个恒星种群的现象，这是在非常高温下起作用的。与欧米茄CEN的最新结果的比较受到无法解释的趋势的阻碍，而光谱k的k丰度的温度有所受到红外apogee数据的有限样本量。然而，很少有疑问是，这两个最庞大的GC在银河系中具有K-mg抗相关性。
Among the multiple stellar populations in globular clusters (GCs) the very high-temperature H-burning regime, able to produce elements up to potassium, is still poorly explored. Here we present the first abundance analysis of K in 42 giants of NGC 6715 (M 54) with homogeneous abundances of light elements previously derived in our FLAMES survey. Owing to the large mass and low metallicity, a large excess of K could be expected in this GC, which is located in the nucleus of the Sagittarius dwarf galaxy. We actually found a spread in [K/Fe] spanning about 1 dex, with [K/Fe] presenting a significant anti-correlation with [O/Fe] ratios, regardless of the metallicity component in M 54. Evidence for a K-Mg anti-correlation also exists, but this is statistically marginal because of the lack of very Mg-poor stars in this GC. We found, however, a strong correlation between K and Ca. These observations clearl y show that the K enhancement in M 54 is probably due to the same network of nuclear reactions generating the phenomenon of multiple stellar populations, at work in a regime of very high temperature. The comparison with recent results in omega Cen is hampered by an unexplained trend with the temperatures for K abundances from optical spectroscopy, and somewhat by a limited sample size for infrared APOGEE data. There are few doubts, however, that the two most massive GCs in the Milky Way host a K-Mg anti-correlation.
