Filling the gap: a new class of old star cluster?
Filling the gap: a new class of old star cluster?
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DOI：
10.1093/mnrasl/slt078
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发表时间：
2013-06
影响因子：
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通讯作者：
D. Forbes;V. Pota;C. Usher;J. Strader;A. Romanowsky;J. Brodie;J. Arnold;L. Spitler
中科院分区：
文献类型：
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作者：
D. Forbes;V. Pota;C. Usher;J. Strader;A. Romanowsky;J. Brodie;J. Arnold;L. Spitler
长寿的星星团是否具有连续的大小和质量（以及密度），或者它们是否应该被视为具有不同起源的不同类型，这一点还不清楚。利用哈勃太空望远镜测量尺寸和凯克10米望远镜的长时间曝光来获得距离，我们发现了第一个确认的星星集群，这些集群位于以前声称的大小-光度差距内，被黄等人称为“回避区”。这些星星集群的存在扩展了星星集群的大小，质量和密度的范围，并反对目前的形成模型，预测明确的大小质量关系（如剥离核，巨大的球状星团或合并星星集群）。这些间隙天体的红色表明它们不是一类新的天体，而是与在附近透镜星系中观察到的微弱模糊有关。我们还报道了一些低光度超紧矮星的大小高达50 pc。既然我们知道星星团具有一系列连续的结构特性，那么未来的统计上完整的研究将受到鼓励。
It is not understood whether long-lived star clusters possess a continuous range of sizes and masses (and hence densities) or if rather, they should be considered as distinct types with different origins. Utilizing the Hubble Space Telescope to measure sizes and long exposures on the Keck 10 m telescope to obtain distances, we have discovered the first confirmed star clusters that lie within a previously claimed size–luminosity gap dubbed the ‘avoidance zone’ by Hwang et al. The existence of these star clusters extends the range of sizes, masses and densities for star clusters, and argues against current formation models that predict welldefined size–mass relationships (such as stripped nuclei, giant globular clusters or merged star clusters). The red colour of these gap objects suggests that they are not a new class of object but are related to faint fuzzies observed in nearby lenticular galaxies. We also report a number of low-luminosity ultracompact dwarfs with sizes of up to 50 pc. Future, statistically complete, studies will be encouraged now that it is known that star clusters possess a continuous range of structural properties.