论文标题
Omega Centauri的MG-K反相关
The Mg-K anti-correlation in Omega Centauri
论文作者
论文摘要
我们使用多对象光谱仪@vlt获得的高分辨率光谱@vlt获得了450颗恒星样品的[k/fe]丰度比。还得出了Fe，Na和Mg的丰度。我们检测到分析恒星中的内在K变化。此外，[k/fe]与[Na/fe]和[mg/fe]的抗相关性显示出显着的相关性。在NGC 2419和NGC 2808之后，明确的MG-K反相关的存在使Omega Centauri成为第三个恒星系统，并托管了[mg/fe] <0.0 dex的恒星，k-enrich of [mg/fe] <0.0 dex，k-enrich ted omega centeriagy在imega centerauri中，由〜0.3 dex与〜0 0. 0. 0. 0. 0. 0. Mg-fe Sarts（Mg-fe）（Mg-fe）（Mg-fe）（MG-g-rich/g。化学异常涉及的K与其他光元素之间的相关性/抗相关性支持以下观点：[K/Fe]中的扩散可以与球状簇的典型自我增强过程相关联。我们认为，在最大和/或金属贫穷的球状簇中可能会发现K丰度的显着变化，这是极端自我增强过程的表现。理论模型面临的问题可以解释球状簇中的K产生。实际上，渐近巨型分支恒星负责MG-K抗相关的模型只与观测值一致。最后，我们发现了一个具有非凡的k过度（[k/fe] =+1.60 dex）的奇特恒星，相对于其他具有相似[mg/fe]的恒星。我们建议，在用原始材料稀释之前，可以从AGB恒星的纯弹射体中形成这种富含K的恒星。
We present [K/Fe] abundance ratios for a sample of 450 stars in Omega Centauri, using high resolution spectra acquired with the multi-object spectrograph FLAMES@VLT. Abundances for Fe, Na and Mg were also derived. We detected intrinsic K variations in the analysed stars. Moreover, [K/Fe] shows a significant correlation with [Na/Fe] and anti-correlation with [Mg/Fe]. The presence of a clear-cut Mg-K anti-correlation makes Omega Centauri the third stellar system, after NGC 2419 and NGC 2808, hosting a sub-population of stars with [Mg/Fe]<0.0 dex, K-enriched in the case of Omega Centauri by ~0.3 dex with respect to the Mg-rich stars ([Mg/Fe]>0.0 dex). The correlation/anti-correlation between K and other light elements involved in chemical anomalies supports the idea that the spread in [K/Fe] can be associated to the same self-enrichment process typical of globular clusters. We suggest that significant variations in K abundances perhaps can be found in the most massive and/or metal-poor globular clusters as manifestation of an extreme self-enrichment process. Theoretical models face problems to explain the K production in globular clusters. Indeed, models where asymptotic giant branch stars are responsible for the Mg-K anti-correlation only qualitatively agree with the observations. Finally, we discovered a peculiar star with an extraordinary K overabundance ([K/Fe]=+1.60 dex) with respect to the other stars with similar [Mg/Fe]. We suggest that this K-rich star could be formed from the pure ejecta of AGB stars before dilution with pristine material.
