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arXiv 0801.2375astro-ph
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麦哲伦星云星团的光学和近红外色与简单恒星星族模型预测的比较

A Comparison of Optical and Near-Infrared Colours of Magellanic Cloud Star Clusters with Predictions of Simple Stellar Population Models

P. M. Pessev, P. Goudfrooij, T. H. Puzia, R. Chandar

摘要:

本文介绍了麦哲伦星云中84个星团的JHK_s 2 MASS积分测光和积分光光学光电测量资料汇编。这些星团的年龄从约2亿年到>10亿年不等,[Fe/H]值从-2.2到-0.1 dex。我们发现,具有相似年龄和金属丰度的星系团的固有颜色存在差异,其中至少有一部分是由于居住在低质量星系团中的明亮恒星数量的随机波动。我们使用54个最可靠的年龄和金属丰度估计作为测试粒子的集群,以评估四个广泛使用的SSP模型在光学/近红外颜色-颜色空间的性能。所有的模型都能很好地再现旧的(>10 Gyr)球状星团的红化校正颜色,但是模型的性能在年轻的时候会有所不同。为了考虑单个星系团的随机涨落效应,我们提供了几个不同年龄段麦哲伦星系团的B-V、B-J、V-J、V-Ks和J-Ks复合色。大多数复合星系团的累积质量都高于保持亮度变化所需的质量,因为随机波动低于10%的水平。在光学-近红外颜色-颜色空间中,复合星系团的颜色在以下年龄间隔中明显不同:>10 Gyr,2-9 Gyr,1-2 Gyr和2亿-1 Gyr。这表明,光学和近红外颜色的组合可以用来区分不同年龄和金属丰度的集群。

英文摘要:

We present integrated JHK_s 2MASS photometry and a compilation of integrated-light optical photoelectric measurements for 84 star clusters in the Magellanic Clouds. These clusters range in age from ~200 Myr to >10 Gyr, and have [Fe/H] values from -2.2 to -0.1 dex. We find a spread in the intrinsic colours of clusters with similar ages and metallicities, at least some of which is due to stochastic fluctuations in the number of bright stars residing in low-mass clusters. We use 54 clusters with the most reliable age and metallicity estimates as test particles to evaluate the performance of four widely used SSP models in the optical/NIR colour-colour space. All models reproduce the reddening-corrected colours of the old (>10 Gyr) globular clusters quite well, but model performance varies at younger ages. In order to account for the effects of stochastic fluctuations in individual clusters, we provide composite B-V, B-J, V-J, V-Ks and J-Ks colours for Magellanic Cloud clusters in several different age intervals. The accumulated mass for most composite clusters are higher than that needed to keep luminosity variations due to stochastic fluctuations below the 10% level. The colours of the composite clusters are clearly distinct in optical-NIR colour-colour space for the following intervals of age: >10 Gyr, 2-9 Gyr, 1-2 Gyr, and 200 Myr-1 Gyr. This suggests that a combination of optical plus NIR colours can be used to differentiate clusters of different age and metallicity.

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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