Bibcode
Williams, B. F.; Durrell, P. R.; Ciardullo, R.; Feldmeier, J. J.; Jacoby, G. H.; Sigurdsson, S.; von Hippel, T.; Ferguson, H.; Tanvir, N.; Arnaboldi, M.; Gerhard, O.; Aguerri, A.; Freeman, K. C.; Vinciguerra, M.
Bibliographical reference
American Astronomical Society Meeting 207, #80.06; Bulletin of the American Astronomical Society, Vol. 37, p.1298
Advertised on:
12
2005
Citations
0
Refereed citations
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Description
Deep HST ACS images of Virgo from the VICS project (Ciardullo et al.)
contain 4 resolved objects that appear to be intergalactic globular
clusters (IGCs). Evidence for this interpretation comes from the
objects' integrated colors and magnitudes, which are consistent with
those of Virgo globulars, their radial surface brightness profiles,
which are well-fit by King models, and from the overdensity of resolved
stars that surround each object. These stars, which have the colors and
magnitudes expected from objects on the red giant branch, show that at
least 2 of the clusters are metal-poor, with [Fe/H] ≲ -1. Taking
the effects of the ACS PSF into account, the best-fit core radii are
≳ 2 pc, possibly larger than those of typical Galactic clusters,
hinting that the objects could be less dynamically evolved than their
Galactic counterparts. The tidal radii of the brightest 2 clusters are
˜ 100 pc; when used in conjunction with models, these radii place
constraints on the objects' origins. The properties of these globular
clusters provide additional information for numerical simulations of the
production of intracluster stars.
Support for this work was provided by NASA through grant number GO-10131
from the Space Telescope Science Institute.