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arXiv 0912.0176astro-ph.SR
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大麦云星云中星协N11的前主序星

Pre-main sequence stars in the stellar association N11 in the Large Magellanic Cloud

Antonella Vallenari, Emanuela Chiosi, Rosanna Sordo

摘要:

麦哲伦云对于研究低金属丰度环境下的恒星形成过程具有极其重要的意义。在本文中,我们报告的发现前主序星的候选人和年轻的嵌入恒星的天体在N11位于大麦云投光的恒星形成的情况。我们要提醒的是,由于在现场发现了很大的年龄差异,这一比较变得复杂。利用深库HST/ACS测光方法,得到了N~11星协和前景星协星群的色-星等图。这些数据的补充档案红外斯皮策数据,使年轻的嵌入恒星物体的检测。将主序前候选星和年轻嵌入恒星天体的空间分布与不同波长观测的文献数据(如H $_α$和CO图)以及OB和Herbig Ae/Be星的分布进行了比较。利用最小生成树方法和两点关联函数得到了聚类度,以了解形成过程。在N11中发现了大量的前主序列候选者。它们的质量范围为1.3-2 MSun,年龄为2 - 10 Myr。年轻的嵌入式恒星的年龄为0.1- 100万年的对象被发现与候选人前主序星混合。恒星的空间分布表明,这一区域是星团形成的产物。年轻的蓝色主序星和暗淡的前主序星的成簇程度没有显著差异,表明它们可能是同一形成过程的一部分。这些数据表明,该地区的恒星形成是一个长期的过程,从0.1到10百万年的恒星广泛分布。

英文摘要:

Magellanic Clouds are of extreme importance to the study of the star formation process in low metallicity environments. In this paper we report on the discovery of pre-main sequence candidates and young embedded stellar objects in N11 located in the Large Magellanic Cloud to cast light on the star formation scenario. We would like to remind that this comparison is complicated by the presence of a large age dispersion detected in the fields. Deep archive HST/ACS photometry is used to derive color-magnitude diagrams of the associations in N~11 and of the foreground field population. These data are complemented by archive IR Spitzer data which allow the detection of young embedded stellar objects. The spatial distribution of the pre-main sequence candidates and young embedded stellar objects is compared with literature data observed at different wavelengths, such as H$_α$ and CO maps, and with the distribution of OB and Herbig Ae/Be stars. The degree of clustering is derived using the Minimal Spanning Tree method and the two point correlation function to get insights about the formation process. A large population of pre-main sequence candidates is found in N11. Their masses are in the range of 1.3-2 MSun for ages from 2 to 10 Myr. Young embedded stellar objects having ages of 0.1-1 Myr are found to be intermixed with the candidate pre-main sequence stars. The spatial distribution of the stars shows that this region is the product of clustered star formation. No significant difference is found in the clustering degree of young blue main sequence stars and faint pre-main sequence candidates, suggesting that they might be part of the same formation process. The data suggest that the star formation in the region is a long-lasting process where stars from 0.1 to 10 Myr are widely distributed.

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