2005A&A...437L..19O

We report the discovery of a large HI cloud in the central regions of the Virgo cluster. It is 110x25kpc in size and contains 3.4x10⁸M_☉ of HI. The morphology and kinematics of this cloud strongly suggest that it consists of HI removed from the galaxy NGC 4388 by ram-pressure stripping. It is more likely the result of an interaction of the ISM of NGC 4388 with the hot halo of the M86 group and not with the ICM centred on M87. The large extent of the plume suggests that gas stripped from cluster galaxies can remain neutral for at least 10⁸yr. Locally, the column density is well above 10²⁰cm^–2, suggesting that the intra-cluster HII regions known to exist in Virgo may have formed from gas stripped from cluster galaxies. The existence of the HI plume suggests that stripping of infalling spirals contributes to the enrichment of the ICM. The HI object in the Virgo cluster recently reported by Minchin et al. (2005ApJ...622L..21M) may have a similar origin and may therefore not be a ``dark galaxy''.