We investigate the connection between globular clusters and ultracompact dwarf galaxies (UCDs) by examining the properties of 10 compact, high-luminosity (-11.8 MV -10.8) objects associated with M87 (NGC 4486, VCC 1316), the cD galaxy in the Virgo Cluster. These objects, most of which were previously classified as M87 globular clusters, were selected from a combination of ground- and space-based imaging surveys. Our observational database for these objects—which we term DGTOs, or "dwarf-globular transition objects"—includes Advanced Camera for Surveys (ACS) F475W and F850LP imaging from the ACS Virgo Cluster Survey, integrated-light spectroscopy from Keck/ESI, and archival F606W WFPC2 imaging. We also present a search for DGTOs associated with other galaxies based on ACS imaging for 100 early-type galaxies in Virgo.

Publication Date



This is the pre-print of an article published by the American Astronomical Society. This final, published version is located here: https://doi.org/10.1086/430342

© 2005 The American Astronomical Society

Also archived in: arXiv: astro-ph/0503566 v1 25 Mar 2005

Support for program GO-9401 was provided through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. P.C. acknowledges additional support provided by NASA LTSA grant NAG5-11714. A.J. acknowledges additional financial support provided by the National Science Foundation through a grant from the Association of Universities for Research in Astronomy, Inc., under NSF cooperative agreement AST 9613615 and by Fundaci´on Andes under project No.C-13442. M.M. acknowledges additional financial support provided by the Sherman M. Fairchild foundation. D.M. is supported by NSF grant AST-020631, NASA grant NAG5-9046, and grant HST-AR-09519.01-A from STScI. M.J.W. acknowledges support through NSF grant AST-0205960. S.G.D. acknowledges a partial support from the Ajax Foundation.

Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in February 2014.

Document Type


Department, Program, or Center

School of Physics and Astronomy (COS)


RIT – Main Campus