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Title

Four faint T dwarfs from the UKIRT Infrared Deep Sky Surveys (UKIDSS) Southern Stripe

Author(s)

Chiu, Kuenley;  Liu, Michael C.;  Jiang, Linhua;  Allers, Katelyn N.;  Stark, Daniel P.;  Bunker, Andrew;  Fan, Xiaohui;  Glazebrook, Karl;  Dupuy, Trent J.

Abstract

We present the optical and near-infrared photometry and spectroscopy of four faint T dwarfs newly discovered from the UKIDSS first data release. The sample, drawn from an imaged area of ∼136 deg2 to a depth of Y = 19.9 (5σ, Vega), is located in the Sloan Digital Sky Survey (SDSS) Southern Equatorial Stripe, a region of significant future deep imaging potential. We detail the selection and followup of these objects, three of which are spectroscopically confirmed brown dwarfs ranging from type T2.5 to T7.5, and one is photometrically identified as early T. Their magnitudes range from Y = 19.01 to 19.88 with derived distances from 34 to 98 pc, making these among the coldest and faintest brown dwarfs known. The T7.5 dwarf appears to be single based on 0.05-arcsec images from Keck laser guide star adaptive optics. The sample brings the total number of T dwarfs found or confirmed by UKIDSS data in this region to nine, and we discuss the projected numbers of dwarfs in the future survey data. We estimate that ∼240 early and late T dwarfs are discoverable in the UKIDSS Large Area Survey (LAS) data, falling significantly short of published model projections and suggesting that initial mass functions and/or birth rates may be at the low end of possible models. Thus, deeper optical data have good potential to exploit the UKIDSS survey depth more fully, but may still find the potential Y dwarf sample to be extremely rare.

Publication type

Journal article

Research centre

Swinburne University of Technology. Faculty of Information and Communication Technologies. Centre for Astrophysics and Supercomputing

Source

Monthly Notices of the Royal Astronomical Society, Vol. 385, no. 1 (Mar 2008), pp. L53-L57

Publication year

2008

FOR Code(s)

0201 Astronomical and Space Sciences;  020104 Galactic Astronomy

Keyword(s)

Catalogues;  Cool brown dwarf;  Discovery;  Infrared stars;  Large-area survey;  Low-mass brown dwarfs;  Photometric system;  Photometric techniques;  Quasars;  Spectral classification;  Spectrograph;  Spectroscopy;  Stars

Publisher

Wiley-Blackwell Publishing

ISSN

0035-8711

Publisher URL

http://dx.doi.org/10.1111/j.1745-3933.2008.00432.x

Copyright

Copyright © 2008 The Authors. Journal compilation Copyright © 2008 RAS.

Full text

Peer reviewed