Star cluster formation and evolution in nearby starburst galaxies – II. Initial conditions
Star cluster formation and evolution in nearby starburst galaxies – II. Initial conditions
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DOI：
10.1046/j.1365-8711.2003.06777.x
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发表时间：
2003-05
影响因子：
4.8
通讯作者：
R. Grijs;P. Anders;N. Bastian;R. Lynds;H. Lamers;E. O'Neil;J. I. O. Astronomy;Cambridge;UK Un
中科院分区：
文献类型：
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作者：
R. Grijs;P. Anders;N. Bastian;R. Lynds;H. Lamers;E. O'Neil;J. I. O. Astronomy;Cambridge;UK Un
我们利用附近星暴星系 NGC 3310 和 NGC 6745 中丰富的年轻星团系统的年龄、质量和金属丰度来推导它们的星团形成历史和随后的演化。通过检查先验假设对单个簇金属丰度的影响，我们进一步扩展了对使用宽带观测来推导这些参数所涉及的系统不确定性的分析（论文 I）。 NGC 3310 核周环中的星团和环外的星团的年龄（和金属丰度）分布在统计上无法区分，但与非环星团样本相比，环中的较高质量星团明显过多；与主星系盘相对静止的环境相比，星暴环中的物理条件可能有利于平均质量更高的星团的形成。对于 NGC 6745 星团系统，我们得出的中位年龄为 10 Myr。 NGC 6745 包含大量高质量“超级星团”，质量范围为 6.5 。 log(Mcl/M⊙) 。 8.0。该检测支持这样的场景：此类物体优先在相互作用星系的极端环境中形成。 NGC 3310 和 NGC 6745 中星团种群的年龄显着低于其各自的特征星团破坏时间尺度，对于 10 4 M⊙ 星团，分别为 log(t dis /yr) = 8.05 和 7.75。这使我们能够获得初始星团质量函数斜率的独立估计，对于质量 Mcl & 10 5 M⊙ 和 Mcl & 4 × 10 5 M⊙，NGC 3310 为 � = 2.04(±0.23) +0.13 −0.43，NGC 6745 为 1.96(±0.15) ± 0.19。这些质量函数斜率与其他质量函数斜率一致
We use the ages, masses and metallicities of the rich young star cluster systems in the nearby starburst galaxies NGC 3310 and NGC 6745 to derive their cluster formation histories and subsequent evolution. We further expand our analysis of the systematic uncertainties involved in the use of broad-band observations to derive these parameters (Paper I) by examining the effects of a priori assumptions on the individual cluster metallicities. The age (and metallicity) distributions of both the clusters in the circumnuclear ring in NGC 3310 and of those outside the ring are statistically indistinguishable, but there is a clear and significant excess of higher-mass clusters in the ring compared to the non-ring cluster sample; it is likely that the physical conditions in the starburst ring may be conducive for the formation of higher-mass star clusters, on average, than in the relatively more quiescent environment of the main galactic disc. For the NGC 6745 cluster system we derive a median age of � 10 Myr. NGC 6745 contains a significant population of high-mass “super star clusters”, with masses in the range 6.5 . log(Mcl/M⊙) . 8.0. This detection supports the scenario that such objects form preferentially in the extreme environments of interacting galaxies. The age of the cluster populations in both NGC 3310 and NGC 6745 is significantly lower than their respective characteristic cluster disruption time-scales, respectively log(t dis /yr) = 8.05 and 7.75, for 10 4 M⊙ clusters. This allows us to obtain an independent estimate of the initial cluster mass function slope, � = 2.04(±0.23) +0.13 −0.43 for NGC 3310, and 1.96(±0.15) ± 0.19 for NGC 6745, respectively, for masses Mcl & 10 5 M⊙ and Mcl & 4 × 10 5 M⊙. These mass function slopes are consistent with those of other