Isolated dwarf galaxies in the local supercluster and its surroundings

Abstract

We present a list of 75 isolated late-type dwarf galaxies which have no neighbors with a relative radial velocity difference of less than 500 km/s or projected separations within 500 kpc. These were selected from $\sim$2000 dwarf galaxies with radial velocities $V_{LG}<3500$ km/s within the volume of the Local supercluster. In terms of their sizes, luminosities, and the amplitudes of their internal motions, the isolated late-type dwarfs do not differ significantly from gas-rich dwarf galaxies in groups and clusters. However, the median mass of neutral hydrogen per unit luminosity for the isolated dwarf galaxies is two times more than that for the late-type galaxies in groups. We have also identified 10 presumably isolated spheroidal dwarf galaxies. The detection of isolated dwarf galaxies populated exclusively by old stars is of great interest for modern cosmological scenarios of galaxy formation.