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Ultracompact dwarfs in the Perseus Cluster: UCD formation via tidal stripping

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  • Dr Samantha Penny
  • Duncan A. Forbes
  • Jay Strader
  • Christopher Usher
  • Jean P. Brodie
  • Aaron J. Romanowsky

We present the results of a Keck/DEIMOS survey of Ultracompact dwarfs (UCDs) in the Perseus Cluster core. We confirm cluster membership for 14 UCDs, with radial velocities ~5300 km s-1. Two of these confirmed that Perseus UCDs have extremely blue colours (B-R < 0.6 mag), reside in star-forming filaments surrounding NGC 1275, and have likely formed as massive star clusters in the last ~100 Myr. We also measure a central velocity dispersion of a third, UCD13 (σ0 = 38 ± 8 km s-1), the most extended UCD in our sample. We determine it to have radius Re = 85 ± 1.1 pc, a dynamical mass of (2.3 ± 0.8) × 108M, and a metallicity [Z/H]= -0.52+0.33-0.29 dex. UCD13 and the cluster's central galaxy, NGC 1275, have a projected separation of 30 kpc and a radial velocity difference of ~20 km s-1. Based on its size, red colour, internal velocity dispersion, dynamical mass, metallicity, and proximity to NGC 1275, we argue that UCD13 is likely the remnant nucleus of a tidally stripped dwarf elliptical (dE), with this progenitor dE having MB ≈ -16 mag and mass ~109M.

Original languageEnglish
Pages (from-to)3808-3816
Number of pages9
JournalMonthly Notices of the Royal Astronomical Society
Volume439
Issue number4
Early online date4 Mar 2014
DOIs
Publication statusPublished - 21 Apr 2014

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  • Ultracompact dwarfs in the Perseus Cluster

    Rights statement: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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