dwarf elliptical galaxyNGC 4627, which is a companion of NGC 4631,[5] is also by default a member of the group, although it is not listed in most catalogs
Aside from these four galaxies, however, the determination of group membership is quite variable. The group lies in a relatively crowded part of the sky near theVirgo Cluster, so exact determination of the group membership is extremely difficult. Some studies have estimated that the NGC 4631 Group contains as few as five galaxies,[4] while others place the estimate as high as 27.[2] Additionally, it is unclear as to whether the galaxies near NGC 4631 and NGC 4656/NGC 4657 form one large group or two smaller groups.[1]
^abcdP. Fouque; E. Gourgoulhon; P. Chamaraux; G. Paturel (1992). "Groups of galaxies within 80 Mpc. II - The catalogue of groups and group members".Astronomy and Astrophysics Supplement.93:211–233.Bibcode:1992A&AS...93..211F.
