Antlia-Sextans Group

NGC 3109, largest and dominant member, optical image from Pan-STARRS Optical Galaxy Survey

The Antlia-Sextans Group is a small Galaxy group in the constellations Hydra, Sextans, Antlia and Leo. It is, on average, approximately 4.3 million light-years away from the Milky Way. It is generally considered to be at the very edge of the Local Group and thus part of it. However, other researchers indicate it is an independent Galaxy group, unlikely to be gravitationally bound to the Local Group due to probably lying outside the Local Group's Zero-velocity surface, and thus the nearest Galaxy group to the Local Group rather than a subgroup within the Local Group.[1] Nonetheless—this possible independence may disappear as the Milky Way continues coalescing with Andromeda due to the increased mass, and density thereof, plausibly widening the radius of the Zero-velocity surface of the Local Group.

  1. ^ van den Bergh, Sidney (June 1999). "The Nearest Group of Galaxies". The Astrophysical Journal. 517 (2): L97–L99. arXiv:astro-ph/9904425. Bibcode:1999ApJ...517L..97V. doi:10.1086/312044.