H I observations of the local group dwarf WLM

Dale C. Jackson, Evan D. Skillman, John M. Cannon, Stéphanie Côté

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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-1 and a total H I mass of (3.2 ± 0.3) × 107 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) × 108 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 × 105 M⊙.

Original languageEnglish (US)
Pages (from-to)1219-1227
Number of pages9
JournalAstronomical Journal
Issue number3 1785
StatePublished - Sep 2004


  • Galaxies: dwarf
  • Galaxies: individual (WLM)
  • Galaxies: irregular
  • Local Group


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