Stellar Populations in NGC 1399 Traced by Globular Clusters from a Wide-Field Study

Abstract.

We present a photometric investigation of the globular cluster population of NGC 1399, the central galaxy in the Fornax cluster, in Washington C and Kron R filters within a field of 36 x 36 arcmin, corresponding to about 200 x 200 kpc at the Fornax distance. This is the largest area around this galaxy ever studied with CCD photometry. The cluster system of NGC 1399 is found to extend further than 100 kpc away from the galaxy. The color distribution exhibits a pronounced bimodality. Within a radial distance of about 55 kpc, the red clusters are more strongly concentrated to the center than the blue clusters. At larger radii, the surface density profiles of the clusters are indistinguishable and match well the distribution of the galaxy light. The cluster system contains $6450 \pm 700$ clusters and the specific frequency is found to be $5.1 \pm 1.2$ in the V band. NGC 1399 shows a pronounced color gradient, which can be interpreted by field populations that are genuinely related to the red and the blue cluster populations.