SCYON Abstract

Received on April 21 2001

Keck Imaging of the Globular Cluster Systems in the Early-type

AuthorsDuncan A. Forbes1, Antonis Georgakakis2 and Jean P. Brodie3
Affiliation1Astrophysics & Supercomputing, Swinburne University, Hawthorn, VIC 3122, Australia,
2School of Physics and Astronomy, University of Birmingham, Edgbaston, B15 2TT, UK,
3Lick Observatory, University of California, Santa Cruz, CA 95064, USA
Accepted byMNRAS


The presence of two globular cluster subpopulations in early-type galaxies is now the norm rather than the exception. Here we present two more examples for which the host galaxy appears to have undergone a recent merger. Using multi-colour Keck imaging of NGC 1052 and NGC 7332 we find evidence for a bimodal globular cluster colour distribution in both galaxies, with roughly equal numbers of blue and red globular clusters. The blue ones have similar colours to those in the Milky Way halo and are thus probably very old and metal-poor. If the red GC subpopulations are at least solar metallicity, then stellar population models indicate young ages. We discuss the origin of globular clusters within the framework of formation models. We conclude that recent merger events in these two galaxies have had little effect on their overall GC systems. We also derive globular cluster density profiles, global specific frequencies and in the case of NGC 1052, radial colour gradients and azimuthal distribution. In general these globular cluster properties are normal for early-type galaxies.