Spatially resolved kinematics of an ultracompact dwarf galaxy

Frank, M. J., Hilker, M., Mieske, S., Baumgardt, H., Grebel E. K. and Infante, L. (2011) Spatially resolved kinematics of an ultracompact dwarf galaxy. Monthly Notices of the Royal Astronomical Society, 414 1: L70-L74. doi:10.1111/j.1745-3933.2011.01058.x


Author Frank, M. J.
Hilker, M.
Mieske, S.
Baumgardt, H.
Grebel E. K.
Infante, L.
Title Spatially resolved kinematics of an ultracompact dwarf galaxy
Journal name Monthly Notices of the Royal Astronomical Society   Check publisher's open access policy
ISSN 0035-8711
1365-2966
Publication date 2011-06-01
Sub-type Article (original research)
DOI 10.1111/j.1745-3933.2011.01058.x
Open Access Status DOI
Volume 414
Issue 1
Start page L70
End page L74
Total pages 5
Place of publication Oxford, United Kingdom
Publisher Oxford University Press
Collection year 2012
Language eng
Formatted abstract
We present the internal kinematics of UCD3, the brightest known ultracompact dwarf galaxy (UCD) in the Fornax cluster, making this the first UCD with spatially resolved spectroscopy. Our study is based on seeing-limited observations obtained with the ARGUS Integral Field Unit of the VLT/FLAMES spectrograph under excellent seeing conditions (0.5–0.67 arcsec FWHM).

The velocity field of UCD3 shows the signature of weak rotation, comparable to that found in massive globular clusters. Its velocity dispersion profile is fully consistent with an isotropic velocity distribution and the assumption that mass follows the light distribution obtained from Hubble Space Telescope imaging. In particular, there is no evidence for the presence of an extended dark matter halo contributing a significant (≳33 per cent within R < 200 pc) mass fraction, nor for a central black hole more massive than ∼5 per cent of the UCD's mass. While this result does not exclude a galaxian origin for UCD3, we conclude that its internal kinematics are fully consistent with it being a massive star cluster.
Keyword Galaxies: dwarf
Galaxies: evolution
Galaxies: kinematics and dynamics
Galaxies: star clusters
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Based on observations obtained at the European Southern Observatory, Chile [Observing Programme 078.B-0496(B)].

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Mathematics and Physics
Official 2012 Collection
 
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Created: Fri, 23 Sep 2011, 02:04:10 EST by Dr Holger Baumgardt on behalf of Physics