The Kinematics of the Ionized Gas in IC 10

Abstract

We present the results of a WIYN integral field unit study of thekinematics of the ionized gas in IC 10, a dwarf irregular starburstgalaxy in the Local Group. Though the velocity field of the ionized gasclosely matches that of the H I, there are several kinematicallyinteresting features in the galaxy. The diffuse ionized gas in thegalaxy exhibits larger H{α} line widths than the bright complexes.In one case this is due to an infusion of energy into the gas associatedwith the radio superbubble discovered by Yang {\amp} Skillman. We findthat the amount of energy in this region is consistent with theirhypothesis that the region contains 10 supernova remnants. We alsodetect a high-velocity (70 km s^{-1}) expanding shell in theionized gas, which is likely driven by three confirmed Wolf-Rayet starsthat are located within the shell. Extrapolating from Hunter's initialmass function, we find that the central starburst region containsapproximately equal energy contributions from stellar winds andsupernovae (SNe), suggesting that SNe are just beginning to play asignificant role in shaping the kinematics of the ionized gas. However,all of this energy cannot be easily accounted for in the kinematics ofthe gas. We detect an energetic flow of gas (3{\times}10^{52}ergs), which we believe originates from the starburst region. We alsodetect a high-velocity (70 km s^{-1}) feature not coincidentwith any structure in our H{α} image. This feature, along with theflow and shell, can account for the energy produced by stellar wind andSNe. The flow resembles one discovered by Wilcots {\amp} Thurow in NGC4214; together they suggest that the porosity of the interstellar mediumcontributes significantly to the high velocity of some portion of theionized gas in irregular galaxies.