A deep WISE search for very late type objects and the discovery of two halo/thick-disc T dwarfs: WISE 0013+0634 and WISE 0833+0052

D.J. Pinfield, J. Gomes, A. C. Day-Jones, S.K. Leggett, M. Gromadzki, B. Burningham, M. T. Ruiz, R. Kurtev, T. Cattermole, C. Cardoso, N. Lodieu, J. Faherty, S. Littlefair, R. Smart, M. Irwin, J. R. A. Clarke, Leigh Smith, P.W. Lucas, M. C. Galvez-Ortiz, J. S. JenkinsH.R.A. Jones, R. Rebolo, V. J. S. Bejar, B. Gauza

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)
90 Downloads (Pure)

Abstract

A method is defined for identifying late-T and Y dwarfs in WISE down to low values of signal-to-noise. This requires a WISE detection only in the W2-band and uses the statistical properties of the WISE multiframe measurements and profile fit photometry to reject contamination resulting from non-point-like objects, variables and moving sources. To trace our desired parameter space, we use a control sample of isolated non-moving non-variable point sources from the Sloan Digital Sky Survey (SDSS), and identify a sample of 158 WISE W2-only candidates down to a signal-to-noise limit of eight. For signal-to-noise ranges >10 and 8-10, respectively, similar to 45 and similar to 90 per cent of our sample fall outside the selection criteria published by the WISE team, mainly due to the type of constraints placed on the number of individual W2 detections. We present follow-up of eight candidates and identify WISE 0013+0634 and WISE 0833+0052, T8 and T9 dwarfs with high proper motion (similar to 1.3 and similar to 1.8 arcsec yr(-1)). Both objects show a mid-infrared/near-infrared excess of similar to 1-1.5 mag and are K band suppressed. Distance estimates lead to space motion constraints that suggest halo (or at least thick disc) kinematics. We then assess the reduced proper motion diagram of WISE ultracool dwarfs, which suggests that late-T and Y dwarfs may have a higher thick-disc/halo population fraction than earlier objects.

Original languageEnglish
Pages (from-to)1009-1026
Number of pages18
JournalMonthly Notices of the Royal Astronomical Society
Volume437
Issue number2
Early online date16 Nov 2013
DOIs
Publication statusPublished - 11 Jan 2014

Keywords

  • surveys
  • brown dwarfs
  • stars: low-mass
  • COOL BROWN DWARF
  • INFRARED-SURVEY-EXPLORER
  • DIGITAL SKY SURVEY
  • EXTRASOLAR GIANT PLANETS
  • INITIAL MASS FUNCTION
  • LARGE-AREA SURVEY
  • BINARY-SYSTEM
  • SPACE DENSITY
  • SPECTRAL CLASSIFICATION
  • LUMINOSITY-FUNCTION

Fingerprint

Dive into the research topics of 'A deep WISE search for very late type objects and the discovery of two halo/thick-disc T dwarfs: WISE 0013+0634 and WISE 0833+0052'. Together they form a unique fingerprint.

Cite this