SIMBAD references

Ensembles of probable physical companions around nearby massive galaxies with V₀<500km/s and M>3x10¹¹M_☉ are derived. Recent estimates of distances for galaxies, a new criterion of membership, and also special searches for diffuse ("spheroidal") dwarf objects have been used for this purpose. Under such an approach the Milky Way has thirteen companions, M31 eleven, M81 fifteen, NGC5128 ten, NGC5236 five, and M101 has seven. According to linear dimension (140kpc), radial velocity dispersion (68km/s), and morphological content (62 percent of E+Sph) the Local Group appears a common one among other systems. Some properties of structure and kinematics of the nearby groups are noted in relation to the luminosity ratio of their two brightest members. The dynamical status of the 6 nearby groups can be explained also without invoking significant amounts of Dark Matter beyond 2-3 standard radii of the principal galaxies.