intergalactic HI cloud

The term intergalactic HI cloud has been used for a volume of observed neutral atomic hydrogen (HI) not associated with an observed galaxy. HI detected beyond the Milky Way generally indicates the presence of a galaxy, but galaxy formation is presumed to begin with star formation in a region without a galaxy, in such an extragalactic HI cloud. Thus any discovery of such a cloud generates interest as do any other signs of star formation at such a location. Such clouds have been discovered, but in some cases, an associated galaxy has subsequently been discovered, e.g., a dwarf galaxy.