University of Hertfordshire

From the same journal

From the same journal

By the same authors

Documents

  • 906825

    Accepted author manuscript, 2 MB, PDF document

  • C. V. Cardoso
  • Leigh Smith
  • S.K. Leggett
  • R.L. Smart
  • A. W. Mann
  • S. Dhital
  • C.G. Tinney
  • Z. Zhang
  • C. Morley
  • D. Saumon
  • K. Aller
  • S. P. Littlefair
  • D. Homeier
  • N. Lodieu
  • Niall Deacon
  • M. S. Marley
  • L. van Spaandonk
  • D. Baker
  • F. Allard
  • A.H. Andrei
  • J. Canty
  • J. Clarke
  • A. C. Day-Jones
  • T. Dupuy
  • J. J. Fortney
  • J. Gomes
  • M. Ishii
  • M. Liu
  • A. Magazzu
  • F. Marocco
  • D. N. Murray
  • B. Rojas-Ayala
  • M. Tamura
View graph of relations
Original languageEnglish
Number of pages41
Pages (from-to)457-497
JournalMonthly Notices of the Royal Astronomical Society
Journal publication dateJul 2013
Volume433
Issue1
DOIs
Publication statusPublished - Jul 2013

Abstract

We report the discovery of 76 new T dwarfs from the UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS). Near-infrared broad- and narrow-band photometry and spectroscopy are presented for the new objects, along with Wide-field Infrared Survey Explorer (WISE) and warm-Spitzer photometry. Proper motions for 128 UKIDSS T dwarfs are presented from a new two epoch LAS proper motion catalogue. We use these motions to identify two new benchmark systems: LHS 6176AB, a T8p+M4 pair and HD 118865AB, a T5.5+F8 pair. Using age constraints from the primaries and evolutionary models to constrain the radii, we have estimated their physical properties from their bolometric luminosity. We compare the colours and properties of known benchmark T dwarfs to the latest model atmospheres and draw two principal conclusions. First, it appears that the H - [4.5] and J - W2 colours are more sensitive to metallicity than has previously been recognized, such that differences in metallicity may dominate over differences in T-eff when considering relative properties of cool objects using these colours. Secondly, the previously noted apparent dominance of young objects in the late-T dwarf sample is no longer apparent when using the new model grids and the expanded sample of late-T dwarfs and benchmarks. This is supported by the apparently similar distribution of late-T dwarfs and earlier type T dwarfs on reduced proper motion diagrams that we present. Finally, we present updated space densities for the late-T dwarfs, and compare our values to simulation predictions and those from WISE.

ID: 7181132