The chemical evolution of dwarf spheroidal galaxies: dissecting the inner regions and their stellar populations
The chemical evolution of dwarf spheroidal galaxies: dissecting the inner regions and their stellar populations
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矮椭球星系的化学演化：剖析内部区域及其恒星群
DOI：
10.1111/j.1365-2966.2008.13175.x
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发表时间：
2008
影响因子：
4.8
通讯作者：
U. Groningen
中科院分区：
文献类型：
--
作者：
A. Marcolini;A. D'ercole;G. Battaglia;B. M. M. F. Astrophysics;U. C. Lancashire;Oss. Astronomico di Bologna;ESOGarching;K. Institute;U. Groningen
利用孤立的矮球状星系（dSphs）的三维流体动力学模拟，我们对其内部区域的化学性质进行了分析，确定了Ia型超新星（SNe Ia）和II型超新星（SNe II）各自所起的作用。来自Ia型超新星的不均匀污染的影响在两个核心半径内表现突出，其中形成的恒星约占总数的20%。与银河系其他地方形成的恒星相比，这些恒星相对富含铁，α元素较少。与预测的恒星速度色散径向轮廓不一致的是，实际的三维图像显示，在中心区域有一个凹陷，在那里富含金属（即富含铁/氢）的恒星被部分分离。这自然导致了两种不同的恒星群，在[Fe/H]和速度色散之间存在反相关关系，就像在雕刻家和天炉座的dsph中观察到的那样。因为我们的模型中最富铁的恒星也是最缺乏α的，所以我们的模型的一个自然预测和测试是，在[α /Fe]和速度色散之间应该存在相同的径向隔离效应。
Using three-dimensional hydrodynamical simulations of isolated dwarf spheroidal galaxies (dSphs), we undertake an analysis of the chemical properties of their inner regions, identifying the respective roles played by Type Ia supernovae (SNe Ia) and Type II supernovae (SNe II). The effect of inhomogeneous pollution from SNe Ia is shown to be prominent within two core radii, with the stars forming therein amounting to similar to 20 per cent of the total. These stars are relatively iron-rich and alpha-element depleted compared to the stars forming in the rest of the galaxy. At odds with the projected stellar velocity dispersion radial profile, the actual three-dimensional one shows a depression in the central region, where the most metal-rich (i.e. [Fe/H]-rich) stars are partly segregated. This naturally results in two different stellar populations, with an anticorrelation between [Fe/H] and velocity dispersion, in the same sense as that observed in the Sculptor and Fornax dSphs. Because the most iron-rich stars in our model are also the most alpha depleted, a natural prediction and test of our model is that the same radial segregation effects should exist between [alpha/Fe] and velocity dispersion.