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arXiv 0909.4234astro-ph.GAastro-ph.COastro-ph.SR
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从矮星系恒星星族色星等图研究其恒星形成历史

Star formation histories of dwarf galaxies from the Colour-Magnitude diagrams of their resolved stellar populations

Michele Cignoni, Monica Tosi

摘要:

在本教程中,我们总结了如何恒星形成(SF)的历史,银河系区域可以从颜色星等图(CMD)的解决恒星。建立合成CMD和利用它们来推导SF历史(SFH)的程序进行了描述,以及相应的不确定性。的SFH解析矮星系的所有形态类型,从应用程序中获得的合成CMD方法,进行了审查和讨论。简而言之:(1)只有早型星系的SF活动有长时间中断的迹象,晚型矮星的SF活动呈现出相当连续的或喘息的SF状态;(2)少数早型矮星只经历过一次集中在最早期的SF活动,而其他许多矮星则表现出延长的或周期性的SF活动;(4)没有发现强SF爆发的频繁证据;(5)矮不规则星和蓝致密矮星的SFH除了当前的SF率外没有显著差异。简要讨论了这些结果对星系形成的影响。

英文摘要:

In this tutorial paper we summarize how the star formation (SF) history of a galactic region can be derived from the colour-magnitude diagram (CMD) of its resolved stars. The procedures to build synthetic CMDs and to exploit them to derive the SF histories (SFHs) are described, as well as the corresponding uncertainties. The SFHs of resolved dwarf galaxies of all morphological types, obtained from the application of the synthetic CMD method, are reviewed and discussed. In short: 1) Only early-type galaxies show evidence of long interruptions in the SF activity; late-type dwarfs present rather continuous, or gasping, SF regimes; 2) A few early-type dwarfs have experienced only one episode of SF activity concentrated at the earliest epochs, whilst many others show extended or recurrent SF activity; 3) No galaxy experiencing now its first SF episode has been found yet; 4) No frequent evidence of strong SF bursts is found; 5) There is no significant difference in the SFH of dwarf irregulars and blue compact dwarfs, except for the current SF rates. Implications of these results on the galaxy formation scenarios are briefly discussed.

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