KINEMATICS AND METALLICITIES IN THE BOOTES III STELLAR OVERDENSITY: A DISRUPTED DWARF GALAXY?

Carlin, Jeffrey L.; Grillmair, Carl J.; Munoz, Ricardo R.; Nidever, David L.; Majewski, Steven R.

Abstract

We report the results of a spectroscopic study of the Bootes 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-circle dot = 197.5 +/- 3.8 km s(-1) and a velocity dispersion of sigma(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.

Más información

Título según WOS: ID WOS:000269053200003 Not found in local WOS DB
Título de la Revista: ASTROPHYSICAL JOURNAL LETTERS
Volumen: 702
Número: 1
Editorial: IOP PUBLISHING LTD
Fecha de publicación: 2009
Página de inicio: L9
Página final: L13
DOI:

10.1088/0004-637X/702/1/L9

Notas: ISI