Observations are reported for 16 of the 25 galaxies found in the Bootes void. At least five of the galaxies are spirals, and another five are disk systems. Two interacting galaxy pairs have been definitely identified, and there are additional candidate pairs. Several of the galaxies are luminous in Hα, due in most cases to significant amounts of star formation. The observed galaxies do not resemble the galaxies predicted to inhabit voids. There is evidence for structure in the spatial distribution of the galaxies, in particular half the galaxies are located in a single plane 10 Mpc wide.

Introduction

The Bootes void, a spherical region with radius 62 Mpc at a distance of 310 Mpc (H0 = 50 km s−1 Mpc−1), is one of the largest known low-density regions in the large-scale distribution of galaxies (Kirshner et al. 1981, 1987). Projected on the sky its diameter subtends an angle of 23°. Identifications of 25 galaxies in Bootes have been published. Almost all of these galaxies were discovered from spectroscopy of samples selected from IRAS and objective prism surveys (see Weistrop et al. 1992 for references). Comparisons with more populated parts of the universe indicate the galaxy density in the Bootes void is about one-third the normal density (Weistrop 1989; Dey, Strauss, & Huchra 1990). This region is therefore a good one in which to investigate the effects of a low-density environment on galaxy evolution, and to compare the nature of the galaxies observed in voids with the predictions of the types of galaxies to be found in voids.