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

Abstract

We report on the radial velocity measurements of 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 present also the radial velocity measurements of some candidates for young and super metal-rich globular clusters, which turn out to be foreground or background objects, viz. 28 stars and 7 galaxies. The bonafide 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 v_{rad} = 1353 +/- 79 km/s, and a velocity dispersion of 338 +/- 56 km/s. 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 rising with radius. Our velocity dispersion estimate 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.