The Recent Formation of Low-Mass Galaxies in the Virgo Cluster

Authors: C. Conselice, J. Gallagher, R. Wyse, & K. O'Neil

Published: 2002 BAAS, preprint


We present evidence for recent evolution and/or formation of early-type low-mass galaxies (LMCGs) in the Virgo cluster based on the results of an Arecibo HI and WIYN optical study. From an 21 cm survey and a search of the literature, we find HI detection claims for nine out of the total 48 observed Virgo objects classified as dwarf ellipticals (dEs) and confirmed as cluster members. For the non-detections we set limits on the HI mass of each non-detection down to ~4x105 Msun. All of the HI-detected objects are located in the outer parts of the cluster. These galaxies are also faint with an average magnitude B = 16.5, compared to B = 14.9 for dEs without detections, similar to dwarf transition types in the nearby universe. Structurally these dwarfs appear as either transition types, with morphologies between dwarf ellipticals and irregulars, or as pure dwarf ellipticals. We also find a general correlation between HI line width and magnitude for these objects, but with a slope much flatter than the Tully-Fisher or Faber-Jackson relationships and with a large scatter. We discuss the possible origins of these objects and conclude that they possibly originate from recent accretion of field galaxies into Virgo that have been transformed by cluster dynamical stripping processes during the last Gyr.