HI properties of nearby galaxies from a volume-limited sample^*

¹ Special Astrophysical Observatory, Russian Academy of Sciences, N.Arkhyz, KChR, 357147, Russia
² Max-Planck-Institut für Radioastronomie, Auf dem Hugel 69, D-53121 Bonn, Germany

Send offprint request to: W.K. Huchtmeier

Received: 25 May 1999
Accepted: 1 July 1999

Abstract

We consider global HI and optical properties of about three hundred nearby galaxies with 500 km s^-1. The majority of them have individual photometric distance estimates. The galaxy sample parameters show some known and some new correlations implying a meaningful dynamic explanation: 1) In the whole range of diameters,  Kpc, the galaxy standard diameter and rotational velocity follows a nearly linear Tully-Fisher relation, 2) The HI mass-to-luminosity ratio and the HI mass-to-"total" mass (inside the standard optical diameter) ratio increase systematically from giant galaxies towards dwarfs, reaching maximum values and 3, respectively. 3) For all the Local Volume galaxies their total mass-to-luminosity ratio lies within a range of [0.2–16] with a median of . The ratio decreases slightly from giant towards dwarf galaxies. 4) The and ratios for the sample galaxies correlate with their mean optical surface brightness, which may be caused by star formation activity in the galaxies. 5) The and ratios are practically independent of the local mass density of surrounding galaxies within the range of densities of about six orders of magnitude. 6) For the LV galaxies their HI mass and angular momentum follow a nearly linear relation: , expected for rotating gaseous disks being near the threshold of gravitational instability, favourable for active star formation.