Hubble Space Telescope Imaging of Globular Cluster Candidates in Low Surface Brightness Dwarf Galaxies

Fifty-seven nearby low surface brightness dwarf galaxies were searched for globular cluster candidates (GCCs) using Hubble Space Telescope WFPC2 imaging in V and I. The sample consists of 18 dwarf spheroidal (dSph), 36 irregular (dIrr), and 3 "transition" type (dIrr/dSph) galaxies with ang...

Full description

Saved in:
Bibliographic Details
Published in:arXiv.org 2005-05
Main Authors: Sharina, Margarita E, Puzia, Thomas H, Makarov, Dmitry I
Format: Article
Language:English
Subjects:
Color
Disk galaxies
Dwarf galaxies
Galactic clusters
Galaxy distribution
Globular clusters
Hubble Space Telescope
Local group (astronomy)
Milky Way Galaxy
Parameters
Populations
Space telescopes
Spheroidal galaxies
Spiral galaxies
Surface brightness
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Fifty-seven nearby low surface brightness dwarf galaxies were searched for globular cluster candidates (GCCs) using Hubble Space Telescope WFPC2 imaging in V and I. The sample consists of 18 dwarf spheroidal (dSph), 36 irregular (dIrr), and 3 "transition" type (dIrr/dSph) galaxies with angular sizes less than 3.7 kpc situated at distances 2-6 Mpc in the field and in the nearby groups: M81, Centaurus A, Sculptor, Canes Venatici I cloud. We find that ~50% of dSph, dIrr/dSph, and dIrr galaxies contain GCCs. The fraction of GCCs located near the center of dwarf spheroidal galaxies is >2 times higher than that for dIrrs. The mean integral color of GCCs in dSphs, V-I = 1.04+/-0.16 mag, coincides with the corresponding value for Galactic globular clusters and is similar to the blue globular cluster sub-populations in massive early-type galaxies. The color distribution for GCCs in dIrrs shows a clear bimodality with peaks near V-I = 0.5 and 1.0 mag. Blue GCCs are presumably young with ages t < 1 Gyr, while the red GCC population is likely to be older. The detected GCCs have absolute visual magnitudes between M_V = -10 and -5 mag. We find indications for an excess population of faint GCCs with M_V > -6.5 mag in both dSph and dIrr galaxies, reminiscent of excess populations of faint globular clusters in nearby Local Group spiral galaxies. The measurement of structural parameters using King-profile fitting reveals that most GCCs have structural parameters similar to extended outer halo globular clusters in the Milky Way and M31, as well as the recently discovered population of "faint fuzzy" clusters in nearby lenticular galaxies.
ISSN:2331-8422
DOI:10.48550/arxiv.0505624