Coma I Group

Structure

The Coma I Group appears to consist of two main subgroups, a denser subgroup centered on NGC 4274 and NGC 4278, and looser one surrounding NGC 4565 as suggested by De Vaucouleurs. However, Gregory and Thompson (1977) found no clear evidence for two distinct subgroups in Coma I. They noted a slight density enhancement around NGC 4274 with the rest of the members of Coma I uniformly distributed to the southeast of this density enhancement. They also noted a central bar-like structure with a minor axis of 0.9 Mpc (2.9 Mly) and a major axis of 2.3 Mpc (7.5 Mly). P. Fouque et al. and A. M. Garcia et al. both list the Coma I group consisting of two subgroups centered on NGC 4274 and NGC 4565. Additionally, Gibson et al. suggests that another association, the Coma II Group which is centered on NGC 4725 is associated with the Coma I Group. In 2000, Ferrarese et al. defined the Coma II Group as containing 5 galaxies, namely NGC 4494, NGC 4562, NGC 4565, NGC 4725, and NGC 4747. Also, it was found that these 5 galaxies which make up the Coma II Group have radial velocities in the narrow range of 1190 to 1395 km/s which is larger than the range of galaxies that are part of the Coma I group which have ranges of 600 to 1000 km/s.