KK246, a dwarf galaxy with extended H I disk in the Local Void

TL;DR

KK 246 is a unique dwarf galaxy in the Local Void with an extremely extended H I disk, unusual kinematic features, and a high mass-to-light ratio, providing insights into galaxy evolution in isolated environments.

Contribution

This study reports the discovery and detailed analysis of KK 246's extended H I disk and kinematic anomalies, highlighting its uniqueness among void galaxies.

Findings

H I disk extends five times beyond the stellar disk

High mass-to-light ratio of 89 indicates a dark matter dominated galaxy

Presence of anomalous velocity H I cloud and kinematic misalignments

Abstract

We have found that KK 246, the only confirmed galaxy located within the nearby Tully Void, is a dwarf galaxy with an extremely extended H I disk and signs of an H I 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 a H I mass of 1.05 +- 0.08 x 10^8 M_sun, and a H I extent 5 times that of the stellar disk, one of the most extended H I disks known. We estimate a dynamical mass of 4.1 x 10^9 M_sun, 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.