We present an analysis of Hubble Space Telescope/WFPC2 images of eighteen galaxies in the Canes Venatici I cloud .
We derive their distances from the luminosity of the tip of the red giant branch stars with a typical accuracy of \sim 12 % .
The resulting distances are 3.9 Mpc ( UGC 6541 ) , 4.9 Mpc ( NGC 3738 ) , 3.0 Mpc ( NGC 3741 ) , 4.5 Mpc ( KK 109 ) , > 6.3 Mpc ( NGC 4150 ) , 4.2 Mpc ( UGC 7298 ) , 4.5 Mpc ( NGC 4244 ) , 4.6 Mpc ( NGC 4395 ) , 4.9 Mpc ( UGC 7559 ) , 4.2 Mpc ( NGC 4449 ) , 4.4 Mpc ( UGC 7605 ) , 4.6 Mpc ( IC 3687 ) , 4.7 Mpc ( KK 166 ) , 4.7 Mpc ( NGC 4736 ) , 4.2 Mpc ( UGC 8308 ) , 4.3 Mpc ( UGC 8320 ) , 4.6 Mpc ( NGC 5204 ) , and 3.2 Mpc ( UGC 8833 ) .
The CVn I cloud has a mean radial velocity of 286 \pm 9 km s ^ { -1 } , a mean distance of 4.1 \pm 0.2 Mpc , a radial velocity dispersion of 50 km s ^ { -1 } , a mean projected radius of 760 kpc , and a total blue luminosity of 2.2 \cdot 10 ^ { 10 } L _ { \sun } .
Assuming virial or closed orbital motions for the galaxies , we estimated their virial and their orbital mass-to-luminosity ratio to be 176 and 88 M _ { \sun } / L _ { \sun } , respectively .
However , the CVn I cloud is characterized by a crossing time of 15 Gyr , and is thus far from a state of dynamical equilibrium .
The large crossing time for the cloud , its low content of dSph galaxies ( < 6 % ) , and the almost “ primordial ” shape of its luminosity function show that the CVn I complex is in a transient dynamical state , driven rather by the free Hubble expansion than by galaxy interactions .