Issue |
A&A
Volume 385, Number 1, April I 2002
|
|
---|---|---|
Page(s) | 21 - 31 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361:20020042 | |
Published online | 15 April 2002 |
New distances to galaxies in the Centaurus A group *,**
1
Special Astrophysical Observatory, Russian Academy of Sciences, N. Arkhyz, KChR, 369167, Russia
2
Isaac Newton Institute, Chile, SAO Branch
3
Kitt Peak National Observatory, National Optical Astronomy Observatories, PO Box 26732, Tucson, AZ 85726, USA
4
Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
5
Departamento de Física, Grupo de Astronomía, Universidad de Concepción, Casilla 160-C, Concepción, Chile
6
UCO/Lick Observatory, University of California at Santa Cruz, Santa Cruz, CA 95064, USA
7
Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195, USA
8
Astronomical Observatory of Kiev University, 04053, Observatorna 3, Kiev, Ukraine
9
Department of Astronomy, University of Florida, Gainesville, FL 32611, USA
10
Department of Astronomy, University of Michigan, 830 Dennison Building, Ann Arbor, MI 48109, USA
Corresponding author: I. D. Karachentsev, ikar@luna.sao.ru
Received:
6
November
2001
Accepted:
8
January
2002
We present Hubble Space Telescope/WFPC2 images of seventeen
dwarf galaxies in the Centaurus A group. Their distances derived from
the magnitudes of the tip of the red giant branch are 5.2 Mpc (KK112),
3.2 Mpc (ESO 321-014), 3.5 Mpc (KK179), 3.4 Mpc (NGC 5102), 4.6 Mpc (KK200),
3.7 Mpc (ESO 324-024), 4.7 Mpc (KK208), 4.6 Mpc (ESO 444-084), 4.4 Mpc
(IC 4316), 4.5 Mpc (NGC 5264), 3.6 Mpc (KK211), 3.6 Mpc (KK213), 3.4 Mpc
(ESO 325-011), 3.8 Mpc (KK217), 4.0 Mpc (KK221), 4.8 Mpc (NGC 5408), and
3.6 Mpc (PGC 51659). The galaxies are concentrated in two spatially separated
groups around NGC 5128 = Cen A and NGC 5236 = M 83. The Cen A group itself
has a mean distance of Mpc, a velocity dispersion of 89 km s-1, a
mean projected radius of 263 kpc, an estimated orbital mass of
,
and an orbital mass-to-blue luminosity ratio of 64
. For the M 83 group we
derived a mean distance of
Mpc, a velocity dispersion of 62 km s-1,
a mean projected radius of 142 kpc, an estimated orbital mass of
,
and
. The M 83 group moves away from the Cen A group, which yields a radius of the zero-velocity surface of the Cen A group of
Mpc. The total mass within
, agrees
with the orbital mass estimate. The centroids of both the groups have very
small peculiar velocities,
km s-1 (Cen A) and (
) km s-1 (M 83)
with respect to the local Hubble flow with
km s-1 Mpc-1.
Key words: galaxies: dwarf / galaxies: distances and redshifts / galaxies: general
© ESO, 2002
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