We report the discovery of a rare isolated group of five dwarf galaxies located at z = 0.0086 (D = 36 Mpc). All member galaxies are star forming, blue, and gas rich, with g − r indices ranging from 0.2 to 0.6 mag, and two of them show signs of ongoing mutual interaction. The most massive member of the group has a stellar mass that is half of the Small Magellanic Cloud stellar mass, and the median stellar mass of the group members is 7.87 × 107M☉. The derived total dynamical mass of the group is Mdyn = 6.02 × 1010M☉, whereas its total baryonic mass (stellar + H i) is 2.6 × 109M☉, which gives us the dynamical to baryonic mass ratio of 23. Interestingly, all galaxies found in the group are aligned along a straight line in the plane of the sky. The observed spatial extent of the member galaxies is 154 kpc, and their relative line-of-sight velocity span is within 75 km s−1. Using the spatially resolved optical spectra provided by the Dark Energy Spectroscopic Instrument early data release, we find that three group members share a common rotational direction. With these unique properties of the group and its member galaxies, we discuss the possible importance of such a system in the formation and evolution of dwarf galaxy groups and in testing the theory of large-scale structure formation.

中文翻译：

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在本地宇宙中发现一组罕见的矮星系


我们报告了一个罕见的孤立的五个矮星系群，位于 z = 0.0086 （D = 36 Mpc）。所有成员星系都是恒星形成的，蓝色的，富含气体，g − r指数范围为0.2到0.6等，其中两个星系显示出持续相互相互作用的迹象。该星系群中质量最大的成员的恒星质量是小麦哲伦星云恒星质量的一半，该星系群成员的恒星质量中位数为 7.87 × 107M☉。该群的总动力质量为 Mdyn = 6.02 × 1010M☉，而其总重子质量（恒星 + H i）为 2.6 × 109M☉，这给我们的动力与重子质量比为 23。有趣的是，在该星系群中发现的所有星系都在天空平面上沿着一条直线排列。观测到的成员星系的空间范围为 154 kpc，它们的相对视线速度跨度在 75 km s−1 以内。利用暗能量光谱仪早期数据发布提供的空间分辨光谱，我们发现三个组成员共享一个共同的旋转方向。利用该星系群及其成员星系的这些独特特性，我们讨论了这样一个系统在矮星系群的形成和演化以及测试大尺度结构形成理论中可能的重要性。