标题： Scl-dE1 GC1：低光度矮椭圆星系中的延展球状星团 显示英文标题

标题： Scl-dE1 GC1: An Extended Globular Cluster in a Low-Luminosity Dwarf Elliptical Galaxy

摘要： 我们报告了从哈勃太空望远镜（HST）的高级巡天相机（ACS）图像中发现的一个球状星团，该星团被命名为Scl-dE1 GC1，位于雕塑星系群中的矮椭球星系Scl-dE1（Sc22）中。 该dE的距离通过色-星等图中红巨星支顶端的I波段星等确定为4.3 +/- 0.25 Mpc。在这个距离上，Scl-dE1 GC1的半光半径约为22 pc，使其成为已知最大的星团之一，特别是对于与矮星系相关的球状星团而言。 Scl-dE1 GC1的绝对星等为Mv = -6.7，并且在数据的测光不确定性范围内，星团的恒星群体似乎与dE的恒星群体没有区别。我们建议矮星系中可能存在两种球状星团形成模式：“正常”模式的半光半径通常为3 pc，以及“扩展”模式的半光半径约为10 pc或更大。 显示英文摘要

摘要： We report the discovery from Hubble Space Telescope ACS images of an extended globular cluster, denoted by Scl-dE1 GC1, in the Sculptor Group dwarf Elliptical galaxy Scl-dE1 (Sc22). The distance of the dE is determined as 4.3 +/- 0.25 Mpc from the I magnitude of the tip of the red giant branch in the color-magnitude diagram. At this distance the half-light radius of Scl-dE1 GC1 is ~22 pc, placing it among the largest clusters known, particularly for globular clusters associated with dwarf galaxies. The absolute magnitude of Scl-dE1 GC1 is Mv = -6.7 and, to within the photometric uncertainties of the data, the cluster stellar population appears indistinguishable from that of the dE. We suggest that there may be two modes of globular cluster formation in dwarf galaxies, a "normal" mode with half-light radii of typically 3 pc, and an "extended" mode with half-light radii of ~10 pc or more.