KK246: A dwarf galaxy with an extended HI disk in the local void

Abstract

We have found that KK246, the only confirmed galaxy located within the nearby Tully Void, is a dwarf galaxy with an extremely extended HI disk and signs of an HI cloud with anomalous velocity. It also exhibits clear misalignment between the kinematical major and minor axes, indicative of an oval distortion, and a general misalignment between the H I and optical major axes. We measure an HI mass of (1.05 ± 0.08) × 108 M ⊙, and an HI extent five times that of the stellar disk, one of the most extended H I disks known. We estimate a dynamical mass of 4.1 × 10 9 M ⊙, making this also one of the darkest galaxies known, with a mass-to-light ratio of 89. The relative isolation and extreme underdense environment make this an interesting case for examining the role of gas accretion in galaxy evolution. © 2011. The American Astronomical Society. All rights reserved.