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arXiv 1406.7121astro-ph.GA
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孤立透镜星系中恒星星族的性质

Properties of Stellar Populations in Isolated Lenticular Galaxies

Ivan Katkov, Olga Sil'chenko, Victor Afanasiev

摘要:

在本文中,我们提出的长缝光谱观测的结果,孤立的透镜状星系的样本,与SCORPIO和SCORPIO-2摄谱仪的6米BTA望远镜的SAO RAS。利用恒星星族演化合成模型的全谱拟合技术,测量了12个目标的恒星视线速度径向分布、速度色散、SSP等效年龄和SSP等效金属丰度。由此产生的平均年龄的恒星星族的凸起和光盘涵盖了整个范围的可能值从1.5至15 Gyr这表明缺乏一定的形成时代的结构组件在孤立的透镜状星系,不像在成员的集群和丰富的群体:他们可能已经形成了在红移的$z>2$以及只有几十亿年前。与密度更大的S 0星系不同,孤立星系通常在凸起和圆盘中具有相同的恒星年龄。在11个星系中的7个星系中,从测光中发现了嵌入盘的透镜和恒星亮度增加的环,就恒星星族和恒星速度色散的性质而言,它们与恒星盘没有很大的区别。我们的结论是,最终形成的透镜状星系的形态类型在完全隔离的关键是依赖于可能的制度,从外面的冷气吸积。

英文摘要:

In this paper we present the results of long-slit spectral observations for a sample of isolated lenticular galaxies, made with the SCORPIO and SCORPIO-2 spectrographs of the 6-meter BTA telescope of the SAO RAS. By applying full spectral fitting technique using the stellar population evolutionary synthesis models, we have measured the radial profiles of the stellar line-of-sight velocity as well as the velocity dispersion, SSP-equivalent age and SSP-equivalent metallicity of stars along the radius in 12 targets. The resulting averaged ages of the stellar population in bulges and discs cover an entire range of possible values from 1.5 to 15 Gyr which indicates the absence of a certain formation epoch for the structural components in the isolated lenticular galaxies, unlike in the members of clusters and rich groups: they could have been formed at a redshift of $z>2$ as well as only a few billion years ago. Unlike S0 galaxies in more dense environments, the isolated galaxies typically have the same age of stars in the bulges and discs. The disc-embedded lenses and rings of increased stellar brightness, identified from the photometry in 7 of 11 galaxies, do not differ strongly from the stellar discs as concerning the properties of stellar populations and stellar velocity dispersion. We conclude that the final shaping of the morphological type of a lenticular galaxy in complete isolation is critically dependent on the possible regimes of cold-gas accretion from outside.

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