Distances to Dwarf Galaxies of the Canes Venatici I Cloud
  We determined the spatial structure of the scattered concentration of
galaxies in the Canes Venatici constellation. We redefined the distances for 30
galaxies of this region using the deep images from the Hubble Space Telescope
archive with the WFPC2 and ACS cameras. We carried out a high-precision stellar
photometry of the resolved stars in these galaxies, and determined the
photometric distances by the tip of the red giant branch (TRGB) using an
advanced technique and modern calibrations. High accuracy of the results allows
us to distinguish the zone of chaotic motions around the center of the system.
A group of galaxies around M94 is characterized by the median velocity VLG=287
km/s, distance D=4.28 Mpc, internal velocity dispersion sigma=51 km/s and total
luminosity LB=1.61x10^10 Lo. The projection mass of the system amounts to
Mp=2.56x10^12 Mo, which corresponds to the mass-luminosity ratio of (M/L)p=159
(M/L)o. The estimate of the mass-luminosity ratio is significantly higher than
the typical ratio M/LB ~30 for the nearby groups of galaxies. The CVnI cloud of
galaxies contains 4-5 times less luminous matter compared with the well-known
nearby groups, like the Local Group, M81 and Centaurus A. The central galaxy
M94 is at least 1 mag fainter than any other central galaxy of these groups.
However, the concentration of galaxies in the Canes Venatici may have a
comparable total mass.
