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arXiv 0809.2295astro-ph
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小麦哲伦星云中恒星结构的演化

Evolution of stellar structure in the Small Magellanic Cloud

M. Gieles, N. Bastian, B. Ercolano

摘要:

本文分析了麦哲伦云测光巡天中小麦哲伦云(SMC)中恒星的投影分布。通过基于V星等和V-I色的标准选择不同年龄的恒星,并研究了作为年龄函数的“分组”程度。我们量化的程度的结构,使用两点关联函数和基于最小生成树的方法,并发现SMC的整体结构是从一个高度的子结构在年轻的年龄(~10百万年),一个平滑的径向密度分布。这种过渡是渐进的,在~ 7500万年时,该分布与背景SMC分布在统计学上无法区分。这个时间尺度近似对应于SMC中恒星的动力学交叉时间。星团在SMC中的空间位置也呈现出类似的空间分布随年龄的演化。我们的分析表明,恒星形成高度的(分形)子结构,可能是由气体的湍流性质,他们的形式,这是擦除随机运动的银河系潜在的时间尺度上的银河系穿越时间的印记。

英文摘要:

The projected distribution of stars in the Small Magellanic Cloud (SMC) from the Magellanic Clouds Photometric Survey is analysed. Stars of different ages are selected via criteria based on V magnitude and V-I colour, and the degree of `grouping' as a function of age is studied. We quantify the degree of structure using the two-point correlation function and a method based on the Minimum Spanning Tree and find that the overall structure of the SMC is evolving from a high degree of sub-structure at young ages (~10 Myr) to a smooth radial density profile. This transition is gradual and at ~75 Myr the distribution is statistically indistinguishable from the background SMC distribution. This time-scale corresponds to approximately the dynamical crossing time of stars in the SMC. The spatial positions of the star clusters in the SMC show a similar evolution of spatial distribution with age. Our analysis suggests that stars form with a high degree of (fractal) sub-structure, probably imprinted by the turbulent nature of the gas from which they form, which is erased by random motions in the galactic potential on a time-scale of a galactic crossing time.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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