Observations of the Local Group Dwarf WLM

We present Australia Telescope Compact Array mosaic H I imaging of the Local Group dwarf irregular galaxy WLM. We find an integrated flux of 149 Jy km s and a total H I mass of (3.2±0.3)×10 M⊙. The major axis of the H I is aligned with the stellar component of the galaxy. The overall H I distribution is relatively smooth at our resolution and has a double peaked central core. One of these peaks is aligned with a region found to have extinction that is internal to WLM and we take this as possible evidence of a large molecular gas complex in the southern half of the galaxy. The other H I peak is in close proximity to the brightest H II regions. WLM’s overall velocity field is consistent with rigid body rotation. A rotation curve is derived, and we find a total dynamical mass of (3.00±0.80)×10 M⊙. We also performed a wide field search, 38 ′ in radius, for H I companions or evidence of recent interactions (e.g., tidal tails), and found no detections to an H I mass limit of MHI > 8.4×10 5 M⊙. Subject headings: galaxies: individual: WLM galaxies: Local Group galaxies: irregular galaxies: dwarf