Kinematics and Metallicities in the Boötes III Stellar Overdensity: A Disrupted Dwarf Galaxy?
Abstract
We report the results of a spectroscopic study of the Boötes III (BooIII) stellar overdensity carried out with the Hectospec multifiber spectrograph on the MMT telescope. Radial velocities have been measured for 193 BooIII candidate stars selected to have magnitudes and colors consistent with its upper main sequence and lower red giant branch, as well as a number of horizontal-branch candidates. From 20 identified candidate BooIII members, we measure a systemic velocity of V_☉ = 197.5 ± 3.8 km s^(–1) and a velocity dispersion of σ_o = 14.0 ± 3.2 km s^(–1). We use the somewhat large velocity dispersion and the implied highly radial orbit, along with morphological evidence from Grillmair and stellar abundances, to argue that BooIII is likely the first known object observed in a transitional state between being a bound dwarf galaxy and a completely unbound tidal stream.
Additional Information
© 2009 American Astronomical Society. Print publication: Issue 1 (2009 September 1); received 2009 June 12; accepted for publication 2009 July 24 Published 2009 August 11. We thank the anonymous referee for helpful suggestions and gratefully acknowledge support by NSF grant AST-0807945 and NASA/JPL contract 1228235.Attached Files
Published - Carlin2009p5805Astrophys_J_Lett.pdf
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Additional details
- Eprint ID
- 15729
- Resolver ID
- CaltechAUTHORS:20090910-122014872
- NSF
- AST-0807945
- NASA/JPL
- 1228235
- Created
-
2009-09-15Created from EPrint's datestamp field
- Updated
-
2021-11-08Created from EPrint's last_modified field
- Caltech groups
- Infrared Processing and Analysis Center (IPAC)