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Globular Cluster Specific Frequency
The globular cluster specific frequency (SN) or the number of GCs (NGC) in a galaxy normalized to MV= -15 mag, was introduced by Harris & van den Bergh (1981) to compare the relative population of globular clusters of early-type galaxies with different sizes and is defined as:
SN = NGC × 10 0.4 ( MV + 15 )




Nuclear Clusters in Dwarf Irregular Galaxies
and
Galactic GCs with Hot Horizontal Branches
A more massive cluster will have a higher capability to retain stellar ejecta than a lower mass one. This subsequently would lead to a higher degree of self-enrichment with processed stellar ejecta from fast evolving massive stars. The degree of such self-enrichment should depend on the cluster escape velocity of stellar ejecta to reach its tidal radius and its metallicity. Thus our primary goal is to quantify and test the viability of such scenario by looking at the escape velocity at the cluster tidal radius. We use the following expression to calculate υesc:


where rh and Mcl are the cluster half-light radius in parsecs and cluster mass in M⊙; fc is a coefficient which takes into account the dependence of the escape velocity on the density profile of the cluster, i.e. its concentration.
!Click on image for full resolution!


Escape velocities for Nuclear clusters and Galactic EHB-GCs
 !Click on image for full resolution!
To appear in Georgiev et al. (2009)

"A small nearby factory for massive star clusters"
!Click on image for full resolution!                                                                                                               Georgiev et al. (2009b)

IKN dSph (high-res)

HST/ACS view of HCG 90
!Click on image for full resolution!                                                                                          Da Rocha, Mieske, Georgiev, et al. (2010)
Color composite Hubble Space Telescope (HST) image of the Hickson Compact Group 90 taken with the Advanced Camera for Surveys (ACS) in F475W & F850LP optical filters, in the blue and red and their average in the green channels, respectively. The two panels show the group in two different intensity scalings. The right panel clearly shows the dusty perturbed disk of one of the HCG 90 members.

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