An extended star cluster at the outer edge of the spiral galaxy M33
Abstract
We report a discovery of an extended globular-like star cluster, M33-EC1, at the outer edge of the spiral galaxy M33. The distance to the cluster is 890 kpc, and it lies at a 12.5 kpc projected distance from the center of M33. Old age (>~7 Gyr) and low metallicity ([M/H] <~ -1.4) are estimated on the basis of isochrone fits. Color-magnitude diagrams of stars, located in the cluster's area, photometric and structural parameters of the cluster are presented. Cluster's luminosity (M_V = -6.6) and half-light radius (r_h = 20.3 pc) are comparable to those of the extended globular clusters, discovered in more luminous Local Group galaxies, the Milky Way and M31. Extended globular clusters are suspected to be remnants of accreted dwarf galaxies, and the finding of such a cluster in the late-type dwarf spiral galaxy M33 would imply a complex merging history in the past.
Keywords
Cite
@article{arxiv.0802.0501,
title = {An extended star cluster at the outer edge of the spiral galaxy M33},
author = {Rima Stonkute and Vladas Vansevicius and Nobuo Arimoto and Takashi Hasegawa and Donatas Narbutis and Naoyuki Tamura and Pascale Jablonka and Kouji Ohta and Yoshihiko Yamada},
journal= {arXiv preprint arXiv:0802.0501},
year = {2009}
}
Comments
20 pages, 6 figures, 2 tables, accepted for publication in AJ