Star cluster collisions - a formation scenario for the extended globular cluster Scl-dE1 GC1 Formation scenario for Scl-dE1 GC1
Star cluster collisions - a formation scenario for the extended globular cluster Scl-dE1 GC1 Formation scenario for Scl-dE1 GC1
复制标题
星团碰撞 - 扩展球状星团 Scl-dE1 GC1 的形成情景 Scl-dE1 GC1 的形成情景
DOI：
10.1111/j.1365-2966.2011.18331.x
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发表时间：
2011
影响因子：
4.8
通讯作者：
Assmann P
中科院分区：
文献类型：
--
作者：
Assmann P
最近对雕塑者星系群中的矮小椭圆星系Sc1-DE1(Sc22)的观测揭示了一个扩展的球状星团(Scl-DE1 Gc1)，它显示出约21.2pC的极大核心半径。这篇发现论文的作者推测，这个天体是否可能存在于它自己的暗物质晕中，和/或它是否可能是通过两个或更多星团的合并形成的。在本文中，我们提出了N-Body模拟来深入探索这一特殊的编队场景。我们追踪一系列质量的暗物质晕内的两个星团的合并(以及在没有暗物质晕的情况下)。为了获得与观测到的扩展星团相似的残留物，我们发现恒星形成效率必须相当高(约33%)，暗物质晕如果存在的话，也必须具有非常低的质量，即在恒星分布的主体内将天体的质量与光比提高至多几倍。我们还发现，单个星团在质量损失后的膨胀提供了另一种可行的形成途径。最后，我们表明，未来对这个系统的速度弥散的测量可能能够区分我们已经探索的各种情景。
Recent observations of the dwarf elliptical galaxy Scl-dE1 (Sc22) in the Sculptor group of galaxies revealed an extended globular cluster (Scl-dE1 GC1), which exhibits an extremely large core radius of about 21.2 pc. The authors of the discovery paper speculate on whether this object could reside in its own dark matter halo and/or if it might have formed through the merging of two or more star clusters. In this paper, we presentN-body simulations to explore thoroughly this particular formation scenario. We follow the merger of two star clusters within dark matter haloes of a range of masses (as well as in the absence of a dark matter halo). In order to obtain a remnant which resembles the observed extended star cluster, we find that the star formation efficiency has to be quite high (around 33 per cent) and the dark matter halo, if present at all, has to be of very low mass, i.e. raising the mass-to-light ratio of the object within the body of the stellar distribution by at most a factor of a few. We also find that expansion of a single star cluster following mass loss provides another viable formation path. Finally, we show that future measurements of the velocity dispersion of this system may be able to distinguish between the various scenarios we have explored.