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
ABSTRACT:
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.