1,026 research outputs found
ACS imaging of 25 galaxies in nearby groups and in the field
We present HST/ACS images and color-magnitude diagrams for 25 nearby galaxies
with radial velocities V_LG < 500 km/s. Distances are determined based on the
luminosities of stars at the tip of the red giant branch that range from 2 Mpc
to 12 Mpc. Two of the galaxies, NGC 4163 and IC 4662, are found to be the
nearest known representatives of blue compact dwarf (BCD) objects. Using
high-quality data on distances and radial velocities of 110 nearby field
galaxies, we derive their mean Hubble ratio to be 68 km/(s Mpc) with standard
deviation of 15 km/(s Mpc). Peculiar velocities of most of the galaxies, V_pec
= V_LG - 68 D, follow a Gaussian distribution with sigma_v = 63 km/s, but with
a tail towards high negative values. Our data displays the known correlation
between peculiar velocity and galaxy elevation above the Local Supercluster
plane. The small observed fraction of galaxies with high peculiar velocities,
V_pec < -500 km/s, may be understood as objects associated with nearby groups
(Coma I, Eridanus) outside the Local volume.Comment: 17 pages, 8 figures, accepted to A
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