The Globular Cluster System of M60 (NGC 4649). I. Canada-France-Hawaii Telescope MOS Spectroscopy and Database
Abstract
We present radial velocity measurements for globular clusters in M60, a giant elliptical galaxy in the Virgo Cluster. Target globular cluster candidates were selected using Washington photometry based on deep 16' × 16' images taken at the KPNO 4 m telescope and using VI photometry derived from Hubble Space Telescope WFPC2 archival images. The spectra of the target objects were obtained with the Multi-Object Spectrograph at the Canada-France-Hawaii Telescope. We have measured the radial velocities of 111 objects in the field of M60: 93 globular clusters (72 blue globular clusters with 1.0 <= C-T1 < 1.7, and 21 red globular clusters with 1.7 <= C-T1 < 2.4), 11 foreground stars, six small galaxies, and the nucleus of M60. The measured velocities of the 93 globular clusters range from ~500 to ~1600 km s-1, with a mean value of 1070+ 27-25 km s-1, which is in good agreement with the velocity of the nucleus of M60 (vgal = 1056 km s-1). Combining our results with data from the literature, we present a master catalog of radial velocities for 121 globular clusters in M60. The velocity dispersion of the clusters in the master catalog is found to be 234+ 13-14 km s-1 for the entire sample, 223+ 13-16 km s-1 for 83 blue globular clusters, and 258+ 21-31 km s-1 for 38 red globular clusters.
Based on observations obtained at the Canada-France-Hawaii Telescope, which is operated by the National Research Council of Canada, the Institut National des Science de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii. This work was organized by the Korea Astronomy and Space Science Institute.- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 2008
- DOI:
- 10.1086/522956
- arXiv:
- arXiv:0709.4308
- Bibcode:
- 2008ApJ...674..857L
- Keywords:
-
- galaxies: individual: M60 &equals NGC 4647;
- galaxies: kinematics and dynamics;
- galaxies: star clusters;
- techniques: spectroscopic;
- Astrophysics
- E-Print:
- 29 pages, 8 figures. To appear in ApJ