Globular Cluster Luminosity Functions and the Hubble Constant from WFPC2 Imaging: Galaxies in the Coma I Cloud

Abstract

The membership of some galaxies in the nearby (d ~ 12 Mpc) Coma I cloud is uncertain. Here we present globular cluster luminosity functions (GCLFs) from the HST for two bright ellipticals which may belong to this group. After fitting the GCLF, we find a turnover magnitude of m_V^0 = 23.23 +/- 0.11 for NGC 4278 and m_V^0 = 23.07 +/- 0.13 for NGC 4494. Our limiting magnitude is about two magnitudes fainter than these values, making this data among the most complete GCLFs published to date. The fitted GCLF dispersions (~ 1.1 mag.) are somewhat smaller than typical values for other ellipticals. Assuming an absolute turnover magnitude of M_V^0 = -7.62, and after applying a small metallicity correction, we derive distance modulii of (m -- M) = 30.61 +/- 0.14 for NGC 4278 and 30.50 +/- 0.15 for NGC 4494. These distance estimates are compared to other methods, and lie within the published range of values. We conclude that both galaxies lie at the same distance and are both members of the Coma I cloud.

13 pages, Latex. Full paper also available at http://www.ucolick.org/~forbes/home.html

Cited by in corpus (13)

• The HST Key Project on the Extragalactic Distance Scale XXVI. The Calibration of Population II Secondary Distance Indicators and the Value of the Hubble Constant
• The Outer Disks of Early-Type Galaxies. I. Surface-Brightness Profiles of Barred Galaxies
• A Database of Cepheid Distance Moduli and TRGB, GCLF, PNLF and SBF Data Useful for Distance Determinations
• An Imaging Survey of Early-Type Barred Galaxies
• M87, Globular Clusters, and Galactic Winds: Issues in Giant Galaxy Formation
• A multivariate statistical analysis of spiral galaxy luminosities. I. Data and results
• HST Imaging of the Globular Clusters in the Fornax Cluster: Color and Luminosity Distributions
• Limits on the accretion rates onto massive black holes in nearby galaxies
• The SLUGGS Survey: Wide Field Imaging of the Globular Cluster System of NGC 4278
• An optical/NIR survey of globular clusters in early-type galaxies. I. Introduction and data reduction procedures
• The HST Key Project on the Extragalactic Distance Scale XVII. The Cepheid Distance to NGC 4725
• A search for ionised gas outflows in an Halpha imaging atlas of nearby LINERs
• The ultraviolet flare at the center of the elliptical galaxy NGC 4278