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arXiv 1101.2869astro-ph.GA
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M51中星团质量相关破裂的新约束

New Constraints on Mass-Dependent Disruption of Star Clusters in M51

Rupali Chandar, Bradley C. Whitmore, Daniela Calzetti, Daiana Di Nino, Robert C. Kennicutt, Michael Regan, Eva Schinnerer

摘要:

我们使用UBVI,Ha图像的漩涡星系,M51,采取与ACS和WFPC 2相机的哈勃太空望远镜(HST)选择星团,并估计它们的质量和年龄,通过比较它们观察到的颜色从人口合成模型的预测。我们构造了中等年龄(1-4x10^8年)星系团的质量函数,发现对于质量大于6x10^3 Msun的星系团,它可以用幂律ψ(M)propto M^beta很好地描述,其中beta=-2.1 +/- 0.2。这将M51中中间年龄星团的质量函数扩展到比以前的测定低近五倍的质量。质量函数在高质量端或低质量端都没有显示出曲率的证据。这种形状表明,没有证据表明与较高质量的对应物相比,较低质量的团簇更早破裂(即,没有质量依赖的破坏)在所观察到的质量和年龄范围内,或为M51中的集群可以形成的物理质量上限Mc。这些结论不同于以前的建议,基于质量较差的HST观测。我们讨论了它们的影响集群的形成和破坏。两个“羽毛”中的星团的年龄,从旋臂的外部延伸的恒星特征,表明具有较大俯仰角的羽毛形成得更早,并且比另一个形成的时间更长。

英文摘要:

We use UBVI,Ha images of the Whirlpool galaxy, M51, taken with the ACS and WFPC2 cameras on the Hubble Space Telescope (HST) to select star clusters, and to estimate their masses and ages by comparing their observed colors with predictions from population synthesis models. We construct the mass function of intermediate age (1-4x10^8 yr) clusters, and find that it is well described by a power law, psi(M) propto M^beta, with beta=-2.1 +/- 0.2, for clusters more massive than approximately 6x10^3 Msun. This extends the mass function of intermediate age clusters in M51 to masses lower by nearly a factor of five over previous determinations. The mass function does not show evidence for curvature at either the high or low mass end. This shape indicates that there is no evidence for the earlier disruption of lower mass clusters compared with their higher mass counterparts (i.e., no mass-dependent disruption) over the observed range of masses and ages, or for a physical upper mass limit Mc with which clusters in M51 can form. These conclusions differ from previous suggestions based on poorer-quality HST observations. We discuss their implications for the formation and disruption of the clusters. Ages of clusters in two "feathers," stellar features extending from the outer portion of a spiral arm, show that the feather with a larger pitch angle formed earlier, and over a longer period, than the other.

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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