Neutral hydrogen clouds near early-type dwarf galaxies of the Local Group

A. Bouchard, C. Carignan, Lister Staveley-Smith

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    28 Citations (Scopus)


    Parkes neutral hydrogen 21 cm line (H I) observations of the surroundings of nine early-type Local Group dwarfs are presented. We detected numerous H I clouds in the general direction of those dwarfs, and these clouds are often offset from the optical center of the galaxies. Although all the observed dwarfs, except Antlia, occupy phase-space regions where the high-velocity cloud (HVC) density is well above average, the measured offsets are smaller than one would expect from a fully random cloud distribution. Possible association is detected for 11 of the 16 investigated clouds, while for two galaxies, Sextans and Leo I, no H I was detected. The galaxies in which H I clouds were found not to coincide with the optical yet have a significant probability of being associated are the Sculptor dwarf, Tucana, LGS 3, Cetus, and Fornax. If the clouds are indeed associated, these galaxies have H I masses of M = 2 × 105, 2 × 106, 7 × 105, 7 × 105, and 1 × 105 Modot, respectively. However, neither ram pressure nor tidal stripping can easily explain the offsets. In some cases, large offsets are found where ram pressure should be the least effective.
    Original languageEnglish
    Pages (from-to)2913-2920
    JournalThe Astronomical Journal
    Issue number6
    Publication statusPublished - 2006


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