A sub-arcsecond study of ionized gas in NGC 253

Abstract

The results of VLA A-configuration observations of ionized gas in the nuclear region of the starburst galaxy NGC 253 using the H92α (8.3 GHz) and H66α (22.4 GHz) recombination lines will be presented. Preliminary analysis of the H66α data has shown RRL emission from several individual compact continuum sources indicating that these sources are high density (ne > 104 cm-3) HII regions. The 8.3 GHz observations are aimed at further studies of unusual kinematics in the central region which was revealed in previous lower resolution (1.5") observations. The unusual kinematics include a strong velocity gradient along the minor axis and possible counter-rotation within the central 25 parsecs. The new sub-arcsecond resolution data is expected to resolve the details of this kinematic sub-system which may have been casued by the combined effects of a bar-potential and a possible mini-merger.