Radial Velocities of Globular Clusters in the Giant Elliptical Galaxy NGC 1399

Abstract

We report radial velocity measurements for 18 globular clusters and one dE galaxy in the field of the giant elliptical galaxy NGC 1399, the dominant galaxy of the Fornax Cluster. We also present radial velocity measurements for some possible young and super–metal-rich globular clusters, which turn out to be foreground or background objects (viz., 28 stars and seven galaxies). The genuine globular clusters are selected, on the basis of their magnitudes and colors, to be metal-rich. For this cluster sample, we measure a mean radial velocity of vrad = 1353 ± 79 km s-1 and a velocity dispersion of σ = 338 ± 56 km s-1. Using a few different mass estimators, this implies M/L values in the range 50–130 within a radius of 28 kpc, consistent with M/L increasing with radius. Our velocity dispersion estimate (σ) is intermediate between the value computed from the integrated stellar light at smaller radii and that computed at large radii from recent X-ray observations.