Local galaxy flows within 5 Mpc ^*,**

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 Herzberg Fellow, Herzberg Institute of Astrophysics, 5071 W. Saanich Road, Victoria, B.C. V9E 2E7, Canada
⁷ Permanent address: UCO/Lick Observatory, University of California at Santa Cruz, Santa Cruz, CA 95064, USA
⁸ Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195, USA
⁹ Astronomical Observatory of Kiev University, 04053, Observatorna 3, Kiev, Ukraine
¹⁰ Department of Astronomy, University of Florida, Gainesville, FL 32611, USA
¹¹ Department of Astronomy, University of Michigan, 830 Dennison Building, Ann Arbor, MI 48109, USA

Corresponding author: M. E. Sharina, sme@luna.sao.ru

Received: 10 September 2002
Accepted: 22 October 2002

Abstract

We present Hubble Space Telescope/WFPC2 images of sixteen dwarf galaxies as part of our snapshot survey of nearby galaxy candidates. We derive their distances from the luminosity of the tip of the red giant branch stars with a typical accuracy of ~12%. The resulting distances are 4.26 Mpc (KKH 5), 4.74 Mpc (KK 16), 4.72 Mpc (KK 17), 4.66 Mpc (ESO 115-021), 4.43 Mpc (KKH 18), 3.98 Mpc (KK 27), 4.61 Mpc (KKH 34), 4.99 Mpc (KK 54), 4.23 Mpc (ESO 490-017), 4.90 Mpc (FG 202), 5.22 Mpc (UGC 3755), 5.18 Mpc (UGC 3974), 4.51 Mpc (KK 65), 5.49 Mpc (UGC 4115), 3.78 Mpc (NGC 2915), and 5.27 Mpc (NGC 6503). Based on distances and radial velocities of 156 nearby galaxies, we plot the local velocity-distance relation, which has a slope of  km s^-1 Mpc^-1 and a radial velocity dispersion of 85 km s^-1. When members of the M81 and Cen A groups are removed, and distance errors are taken into account, the radial velocity dispersion drops to  km s^-1. The local Hubble flow within 5 Mpc exhibits a significant anisotropy, with two infall peculiar velocity regions directed towards the Supergalactic poles. However, two observed regions of outflow peculiar velocity, situated on the Supergalactic equator, are far away (~50°) from the Virgo/anti-Virgo direction, which disagrees with a spherically symmetric Virgo-centric flow. About 63% of galaxies within 5 Mpc belong to known compact and loose groups. Apart from them, we found six new probable groups, consisting entirely of dwarf galaxies.