A SEARCH FOR GAS-RICH DWARF GALAXIES JUST OUTSIDE THE LOCAL SUPERCLUSTER

The nearest void in the distribution of galaxies, in a direction perpendicular to the fundamental plane of the Local Supercluster, has been sampled in the neutral hydrogen spectral line for low-mass gas clouds or H I-rich dwarf galaxies. None were found, to a smaller H I mass limit than has been previously reported for a low density region in the large-scale distribution of galaxies. We can give a formal upper limit of about 5% of closure density in the form of gas clouds with M(H) greater than or similar to 5 X 10(6) M . if they are assumed to "fill the voids." In fact, it is more likely that the ratio of gas-rich dwarfs to spirals is no higher in voids than in superclusters, and that dwarf irregular galaxies with M(H) below 10(8) M. are less common than galaxies of greater mass. Two new members of a previously detected group of galaxies at a redshift of approximately 2500 km s-1, representing an "island" in the void, were detected, along with four galaxies in the background.