发表机构
Space Telescope Science Institute; Special Astrophysical Observatory, Russian Academy of Sciences; University of Washington; University of California Berkeley; University of Hawaii; Johns Hopkins University; Raytheon; University of Arizona; University of Maryland（太空望远镜科学研究所; 俄罗斯科学院特殊天体物理观测台; 华盛顿大学; 加州大学伯克利分校; 夏威夷大学; 约翰斯·霍普金斯大学; 雷神公司; 亚利桑那大学; 马里兰大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
利用HST解析恒星，测定孤立矮星系KDG 162距离为3.48 Mpc，发现其近期恒星形成有限，恒星质量为H I的两倍，为低质量星系演化提供新观测证据。
AI 中文摘要
邻近矮星系KDG 162（也称为KK 153）近来因其可能是一个富含气体、孤立且低质量的矮星系而受到关注。然而，这些特征中的许多都依赖于KDG 162的真实距离。本文展示了新的哈勃空间望远镜（HST）成像，该成像解析了红巨星分支尖端以下3个星等内的单颗恒星。利用这些HST成像，我们确定KDG 162的距离为D = 3.48 ± 0.12 Mpc，略高于之前的测定值。我们发现KDG 162相对孤立，位于首次落入M81星系群的边缘。我们利用其恒星含量测量了其近期恒星形成历史，发现仅在过去约500 Myr内存在适度的恒星形成活动。当前的恒星质量是H I质量的2倍。KDG 162的性质为邻近孤立低质量星系的日益详细图景增添了内容。未来，更深的观测将能够触及对年龄更敏感的恒星族群，从而恢复其远古时期的恒星形成历史。
英文摘要
The nearby dwarf galaxy KDG 162 (also known as KK 153) has recently attracted attention as a potentially gas-rich, isolated, and low-mass dwarf galaxy. However, many of these characterizations depend on the true distance to KDG 162. Here we present new Hubble Space Telescope (HST) imaging that resolves individual stars down to 3 magnitudes below the tip of the red giant branch. Using this HST imaging, we determine a distance to KDG 162 of D = 3.48 $\pm$ 0.12 Mpc, somewhat higher than previous determinations. We find KDG 162 to be relatively isolated and lying at the edge of first infall onto the M81 group. We use its stellar content to measure its recent star formation history and find that only a modest amount of star formation can be attributed to within the last $\sim$500 Myr. The present-day stellar mass outweighs the H I mass by a factor of 2$\times$. The properties of KDG 162 add to an increasingly detailed picture of nearby and isolated low-mass galaxies. In the future, deeper observations would allow for reaching more age-sensitive populations, enabling the recovery of its star-formation history back to ancient times.
Comments8 pages, 7 figures, submitted to AJ. comments welcome and appreciated
