论文标题
仙女座银河系中极缺乏金属的球状簇
An extremely metal-deficient globular cluster in the Andromeda Galaxy
论文作者
论文摘要
球状簇（GC）是密集的，重力结合的系统，成千上万的恒星。它们优先与星系的最古老组成部分相关，因此它们的组成的测量可以提供对早期宇宙中星系中化学元素的堆积的见解。我们报告了仙女座银河系（M31）中的大量GC，该GC在沉重的元素中极度耗尽。它的铁丰度比太阳低约800倍，比以前已知的最贫穷的GC低三倍。它在镁中也大大耗尽。这些测量值挑战了GC的金属度地板的概念，以及理论上的期望，即在如此低的金属性下不可能形成大量的GC。
Globular clusters (GCs) are dense, gravitationally bound systems of thousands to millions of stars. They are preferentially associated with the oldest components of galaxies, and measurements of their composition can therefore provide insight into the build-up of the chemical elements in galaxies in the early Universe. We report a massive GC in the Andromeda Galaxy (M31) that is extremely depleted in heavy elements. Its iron abundance is about 800 times lower than that of the Sun, and about three times lower than in the most iron-poor GCs previously known. It is also strongly depleted in magnesium. These measurements challenge the notion of a metallicity floor for GCs and theoretical expectations that massive GCs could not have formed at such low metallicities.
