A group of galaxies around the giant spiral NGC 6946

TL;DR

This study identifies and characterizes a nearby galaxy group around NGC 6946, revealing its members, distances, and physical properties through CCD imaging and HI line observations.

Contribution

It reports the discovery and detailed analysis of a galaxy group near NGC 6946, including new dwarf irregular galaxies and their properties.

Findings

Mean distance to the group is 5.9 Mpc.

The group has a diameter of 420 kpc.

Virial mass-to-luminosity ratio is about 56 M_sun/L_sun.

Abstract

We present large-scale CCD images of a dozen low surface brightness objects in the vicinity of giant Sc galaxy NGC 6946, which have been found recently on POSS-II copies. Six of them: UGC 11583, kk251, kk252, kkr55, kkr56, and kkr59 are dwarf irregular galaxies resolved into stars. We determined their distances from the luminosity of the brightest blue stars. The mean estimated distance to the NGC 6946 group is 5.9 +- 0.4 Mpc. Together with Cepheus 1, discovered before, the group consist of 8 late type galaxies. Almost all of them are detected or marginally detected in the HI line. The group is characterized by a linear projected diameter of 420 kpc, a radial velocity dispersion of 95 km/s, and a virial mass-to-luminosity ratio about 56 M_sun/L_sun.