球状星团M53（NGC5024）中的蓝离散星群：HST、LBT、CFHT的联合研究
The Blue Straggler population in the globular cluster M53 (NGC5024): a combined HST, LBT, CFHT study
摘要：
我们使用了一个适当的组合，多波段高分辨率和宽视场多波长观测收集在三个不同的望远镜（HST，LBT和CFHT）探测蓝色离散星（BSS）人口的球状星团M53。在整个集群扩展范围内已确定了近200个BSS。这些恒星的径向分布是双峰的（类似于其他几个星团的分布），在距星团中心约60“（~2 r_c）处有一个明显的倾角。这个值比回避半径（r_avoid，在哈勃时间内，由于动力学摩擦效应，所有~1.2 M_sun的恒星都沉入核心的半径）小2倍。虽然在大多数具有双峰BSS径向分布的集群中，已发现r_avoid位于观察到的最小值区域中，但这是第二种情况（在NGC 6388之后），其中注意到这种差异。这一证据表明，在少数星系团中，动力学摩擦的效率似乎比预期的要低。我们还使用这个数据库来构建星团的径向恒星密度分布图：这是迄今为止为该星团发布的最广泛和最准确的径向分布图，包括非常内部区域的详细恒星计数。恒星的密度分布是由一个标准的King模型再现的，该模型具有一个扩展的核心（~ 25“）和一个中等的浓度参数值（c=1.58）。在簇的最外部区域（距中心r>6.5'处）注意到与模型的偏离。这一特点需要进一步研究，以解决可能存在的潮汐尾在这个集群。
英文摘要：
We used a proper combination of multiband high-resolution and wide field multi-wavelength observations collected at three different telescopes (HST, LBT and CFHT) to probe Blue Straggler Star (BSS) populations in the globular cluster M53. Almost 200 BSS have been identified over the entire cluster extension. The radial distribution of these stars has been found to be bimodal (similarly to that of several other clusters) with a prominent dip at ~60'' (~2 r_c) from the cluster center. This value turns out to be a factor of two smaller than the radius of avoidance (r_avoid, the radius within which all the stars of ~1.2 M_sun have sunk to the core because of dynamical friction effects in an Hubble time). While in most of the clusters with a bimodal BSS radial distribution, r_avoid has been found to be located in the region of the observed minimum, this is the second case (after NGC6388) where this discrepancy is noted. This evidence suggests that in a few clusters the dynamical friction seems to be somehow less efficient than expected. We have also used this data base to construct the radial star density profile of the cluster: this is the most extended and accurate radial profile ever published for this cluster, including detailed star counts in the very inner region. The star density profile is reproduced by a standard King Model with an extended core (~25'') and a modest value of the concentration parameter (c=1.58). A deviation from the model is noted in the most external region of the cluster (at r>6.5' from the center). This feature needs to be further investigated in order to address the possible presence of a tidal tail in this cluster.
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。
