On the Neutral Gas Content and Environment of NGC 3109 and the Antlia Dwarf Galaxy

Abstract

As part of a continuing survey of nearby galaxies, we have mapped theneutral gas content of the low surface brightness Magellanic-type galaxyNGC 3109 and its environment, including the Antlia dwarf galaxy, atunprecedented velocity resolution and brightness sensitivity. The H Imass of NGC 3109 is measured to be 3.8+/-0.5{\times}10^{8}M_{solar}. A substantial warp in the disk of NGC 3109 isdetected in the H I emission image in the form of an extended lowsurface brightness feature. We report a positive detection in H I of thenearby Antlia dwarf galaxy and measure its total neutral gas mass to be6.8+/-1.4{\times}10^{5} M_{solar}. We show the warp inNGC 3109 to lie at exactly the same radial velocity as the gas in theAntlia dwarf galaxy and speculate that Antlia disturbed the disk of NGC3109 during a mild encounter ~1 Gyr in the past. H I data for a furthereight galaxies detected in the background are presented.