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Probing the boundary between star clusters and dwarf galaxies: A MUSE view on the dynamics of Crater/Laevens I

Voggel, K, Hilker, M, Baumgardt, H, Collins, MLM, Grebel, EK, Husemann, B, Richtler, T and Frank, MJ (2016) Probing the boundary between star clusters and dwarf galaxies: A MUSE view on the dynamics of Crater/Laevens I Monthly Notices of the Royal Astronomical Society, 460 (3). pp. 3384-3397.

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Abstract

We present MUSE observations of the debated ultra faint stellar system Crater. We spectroscopically confirm 26 member stars of this system via radial velocity measure-ments. We derive the systematic instrumental velocity uncertainty of MUSE spectra to be 2.27kms−1. This new dataset increases the confirmed member stars of Crater by a factor of 3. One out of three bright blue stars and a fainter blue star just above the main-sequence-turn-off are also found to be likely members of the system. The ob-servations reveal that Crater has a systemic radial velocity of vsys = 148.18+1.08−1.15 kms−1, whereas the most likely velocity dispersion of this system is σv = 2.04+2.19−1.06 kms−1. The total dynamical mass of the system, assuming dynamical equilibrium is thenMtot = 1.50+4.9−1.2 · 105M implying a mass-to-light ratio of M/LV=8.52+28.0−6.5 M/L, which is consistent with a purely baryonic stellar population within its errors and no sig-nificant evidence for the presence dark matter was found. We also find evidence for a velocity gradient in the radial velocity distribution. We conclude that our findings strongly support that Crater is a faint intermediate-age outer halo globular cluster and not a dwarf galaxy.

Item Type: Article
Subjects : subj_Physics
Authors :
AuthorsEmailORCID
Voggel, KUNSPECIFIEDUNSPECIFIED
Hilker, MUNSPECIFIEDUNSPECIFIED
Baumgardt, HUNSPECIFIEDUNSPECIFIED
Collins, MLMUNSPECIFIEDUNSPECIFIED
Grebel, EKUNSPECIFIEDUNSPECIFIED
Husemann, BUNSPECIFIEDUNSPECIFIED
Richtler, TUNSPECIFIEDUNSPECIFIED
Frank, MJUNSPECIFIEDUNSPECIFIED
Date : 12 May 2016
Identification Number : 10.1093/mnras/stw1132
Copyright Disclaimer : Copyright 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.
Related URLs :
Depositing User : Symplectic Elements
Date Deposited : 10 May 2016 17:31
Last Modified : 19 Jul 2016 13:04
URI: http://epubs.surrey.ac.uk/id/eprint/810662

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