2 research outputs found
HST Imaging of the Globular Clusters in the Fornax Cluster: NGC 1399 and NGC 1404
The Fornax cluster galaxies NGC 1399 and NGC 1404 are ideal for studying the
effects of a cluster environment on globular cluster systems. Here we present
new optical imaging of these two galaxies from both the Hubble Space
Telescope's Wide Field and Planetary Camera 2 and the Cerro Tololo
Inter-American Observatory's 1.5m telescope. The combination of both data sets
provides unique insight on the spatial and colour distribution of globular
clusters. From B-I colours, we find that both galaxies have a broad globular
cluster metallicity distribution that is inconsistent with a single population.
Two Gaussians provide a reasonable representation of the metallicity
distribution in each galaxy. The metal-rich subpopulation is more centrally
concentrated than the metal-poor one. We show that the radial metallicity
gradient can be explained by the changing relative mix of the two globular
cluster subpopulations. We derive globular cluster surface density profiles,
and find that they are flatter (i.e. more extended) than the underlying
starlight. The total number of globular clusters and specific frequency are
calculated to be N = 5700 +/- 500, S_N = 11.5 +/- 1.0 for NGC 1399 and N = 725
+/- 145, S_N = 2.0 +/- 0.5 for NGC 1404. Our results are compared to the
expectations of globular cluster formation scenarios.Comment: 21 pages, Latex, 13 figures, submitted to MNRA