An optical search for the intergalactic H I cloud in Leo

Abstract

An optical search has been made for the large intergalactic H I cloud discovered from Arecibo by Schneider et al. A very deep red UKSTU plate of the area has been scanned by the APM machine and deep CCD frames of a small area near a peak in the H I emission have been acquired. No extended emission is found at the limiting surface brightness of the photographic material ≅26.3 Rµ and no excess of stars above that expected from our Galaxy is found in the CCD data. However, due to the extreme size of the H I cloud, the upper limit on the total luminosity is that of a dwarf galaxy, MB ≳ −18. As its hydrogen and total masses would not be unusual for a galaxy, a highly extended very low surface brightness galaxy can not be ruled out, at present.