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arXiv 1302.0927astro-ph.GA
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双星演化在早型星系紫外光谱拟合中的潜在重要性

Potential Importance of Binary Evolution in UV-Optical Spectral Fitting of Early-Type Galaxies

Zhongmu Li, Caiyan Mao, Li Chen, Qian Zhang, Maocai Li

摘要:

双星在星系中非常常见,超过一半的银河系热亚矮星被认为是古老恒星星族紫外线上升的可能来源,在双星中发现。以往的工作表明,双星演化可以使双星种群的光谱与单星种群的光谱有显著的不同。然而,大多数星系光谱拟合工作都没有考虑双星演化的影响。本文通过一个包含单星和双星两种星族的恒星星族综合模型,研究了双星演化在早型星系光谱拟合中的作用。拟合了从紫外到可见波段的光谱,确定了星系的一些参数。结果表明,在恒星星族模型中加入双星可能会导致某些星系参数的确定发生明显变化,因此对光谱研究具有潜在的重要意义。特别是,当使用双星星族模型而不是单星星族模型时,复合恒星星族的年轻组分的年龄变得更老。这意味着双星人口模型将测量显着不同的恒星形成历史(SFHS)的星系相比,单星人口模型。此外,具有双星相互作用的恒星星族模型比单恒星族模型平均测量更大的尘埃散射。这表明,当用双星星族模型代替单星星族模型时,在对早型星系进行光谱拟合时,可能不需要负折射。

英文摘要:

Binaries are very common in galaxies, and more than half of Galactic hot subdwarf stars, which are thought as a possible origin of UV-upturn of old stellar populations, are found in binaries. Previous works showed that binary evolution can make the spectra of binary star populations significantly different from those of single star populations. However, the effect of binary evolution has not been taken into account in most works of spectral fitting of galaxies. This paper studies the role of binary evolution in spectral fitting of early-type galaxies, via a stellar population synthesis model including both single and binary star populations. Spectra from ultraviolet to optical band are fitted to determine a few parameters of galaxies. The results show that the inclusion of binaries in stellar population models may lead to obvious change in the determination of some galaxy parameters and therefore it is potentially important for spectral studies. In particular, the ages of young components of composite stellar populations become much older when using binary star population models instead of single star population models. This implies that binary star population models will measure significantly different star formation histories (SFHs) for galaxies compared to single star population models. In addition, stellar population models with binary interactions measure larger dust extinctions than single star population models on average. It suggests that when using binary star population models instead of single star population models, negative extinctions are possibly unnecessary in spectral fitting of early-type galaxies.

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