Population Gradients in Local Group Dwarf Spheroidal Galaxies
Population Gradients in Local Group Dwarf Spheroidal Galaxies
复制标题
本星系群矮球状星系中的种群梯度
DOI：
10.1086/324232
复制
发表时间：
2001
期刊：
影响因子：
--
通讯作者：
M. Mateo
中科院分区：
文献类型：
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作者：
D. Harbeck;E. Grebel;J. Holtzman;P. Guhathakurta;W. Brandner;D. Geisler;A. Sarajedini;A. Dolphin;D. Hurley;M. Mateo
我们提出了一个系统的和均匀的分析人口梯度的本集团矮球状星系（dSph的）船底座，玉夫座，六分仪座，杜鹃座，仙女座I-III，V和VI。对于这里研究的所有银河系同伴，我们发现了显着的人口梯度。位于Local Group外围的远程dSph Tucana也是如此。在M31 dSph伴星中，只有仙女座I和VI表现出明显的梯度。在所有可见水平分支（HB）形态梯度的情况下，红色HB星都更集中。HB形态梯度的出现与红巨星分支的形态梯度相关。金属丰度似乎是六分仪座、玉夫座、杜鹃座和仙女座VI的梯度的驱动力，而年龄是船底座的一个重要因素。我们没有发现任何证据表明附近的大质量螺旋星系影响人口梯度的形成。
We present a systematic and homogeneous analysis of population gradients for the Local Group dwarf spheroidal galaxies (dSph's) Carina, Sculptor, Sextans, Tucana, and Andromeda I–III, V, and VI. For all of the Milky Way companions studied here, we find significant population gradients. The same is true for the remote dSph Tucana located at the outskirts of the Local Group. Among the M31 dSph companions, only Andromeda I and VI show obvious gradients. In all cases where a horizontal-branch (HB) morphology gradient is visible, the red HB stars are more centrally concentrated. The occurrence of a HB morphological gradient shows a correlation with a morphology gradient in the red giant branch. It seems likely that metallicity is the driver of the gradients in Sextans, Sculptor, Tucana, and Andromeda VI, while age is an important factor in Carina. We find no evidence that the vicinity of a nearby massive spiral galaxy influences the formation of the population gradients.