Colliding and merging galaxies. II - S0 galaxies with polar rings

Abstract

A detailed optical study of A0136-0801, a newly discovered spindle galaxy, is presented, and the structure, origin, and evolution of ringed S0 galaxies in general are discussed. Photographic photometry and spectroscopy of the galaxy are described, and quantitative results are presented for the galaxy's morphology and geometry, photometry of the spindle, brightness and H I content of the ring, rotation of spindle and ring, and velocity dispersion of the spindle. The spindle is a normal S0 disk seen nearly edge-on; the ring motions suggest that a massive halo extends far beyond the S0 disk and is more spherical than flat. From a study of 22 related galaxies, it is found that a few percent of all field S0's possess near-polar rings or disks. It is suggested that these structures are due to a second event, most likely the transfer of mass from a companion galaxy during a close encounter and occasionally also the merger of a companion.