47 new T dwarfs from the UKIDSS Large Area Survey

  1. Ben Burningham1,*,
  2. D. J. Pinfield1,
  3. P. W. Lucas1,
  4. S. K. Leggett2,
  5. N. R. Deacon3,
  6. M. Tamura4,
  7. C. G. Tinney5,
  8. N. Lodieu6,7,
  9. Z. H. Zhang1,
  10. N. Huelamo8,
  11. H. R. A. Jones1,
  12. D. N. Murray1,
  13. D. J. Mortlock9,
  14. M. Patel9,
  15. D. Barrado y Navascués8,
  16. M. R. Zapatero Osorio8,
  17. M. Ishii10,
  18. M. Kuzuhara11,
  19. R. L. Smart12

Article first published online: 27 MAY 2010

DOI: 10.1111/j.1365-2966.2010.16800.x

Issue

Monthly Notices of the Royal Astronomical Society

Monthly Notices of the Royal Astronomical Society

Volume 406, Issue 3, pages 1885–1906, August 2010

Additional Information

How to Cite

Burningham, B., Pinfield, D. J., Lucas, P. W., Leggett, S. K., Deacon, N. R., Tamura, M., Tinney, C. G., Lodieu, N., Zhang, Z. H., Huelamo, N., Jones, H. R. A., Murray, D. N., Mortlock, D. J., Patel, M., Barrado y Navascués, D., Zapatero Osorio, M. R., Ishii, M., Kuzuhara, M. and Smart, R. L. (2010), 47 new T dwarfs from the UKIDSS Large Area Survey. Monthly Notices of the Royal Astronomical Society, 406: 1885–1906. doi: 10.1111/j.1365-2966.2010.16800.x

Author Information

  1. 1

    Centre for Astrophysics Research, Science and Technology Research Institute, University of Hertfordshire, Hatfield AL10 9AB

  2. 2

    Gemini Observatory, 670 N. A'ohoku Place, Hilo, HI 96720, USA

  3. 3

    Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA

  4. 4

    National Astronomical Observatory, Mitaka, Tokyo 181-8588, Japan

  5. 5

    School of Physics, University of New South Wales, NSW 2052, Australia

  6. 6

    Instituto de Astrofísica de Canarias, 38200 La Laguna, Spain

  7. 7

    Departamento de Astrofísica, Universidad de La Laguna, E-38205 La Laguna, Tenerife, Spain

  8. 8

    Centro de Astrobiologia (CSIC-INTA) E-28850 Torrejón de Ardoz, Madrid, Spain

  9. 9

    Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ

  10. 10

    Subaru Telescope, 650 North A'ohoku Place, Hilo, Hi 96720, USA

  11. 11

    University of Tokyo, Hongo, Tokyo 113-0033, Japan

  12. 12

    Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Torino, Strada Osservatrio 20, 10025 Pino Torinese, Italy

* E-mail: b.burningham@herts.ac.uk

Publication History

  1. Issue published online: 3 AUG 2010
  2. Article first published online: 27 MAY 2010
  3. Accepted 2010 April 2. Received 2010 March 3; in original form 2009 December 23

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Keywords:

  • surveys;
  • brown dwarfs;
  • stars: low-mass

ABSTRACT

We report the discovery of 47 new T dwarfs in the Fourth Data Release (DR4) from the Large Area Survey (LAS) of the United Kingdom Infrared Telescope (UKIRT) Infrared Deep Sky Survey with spectral types ranging from T0 to T8.5. These bring the total sample of LAS T dwarfs to 80 as of DR4. In assigning spectral types to our objects we have identified eight new spectrally peculiar objects, and divide seven of them into two classes. H2O-H-early have a H2O-H index that differs with the H2O-J index by at least two subtypes. CH4-J-early have a CH4-J index that disagrees with the H20-J index by at least two subtypes. We have ruled out binarity as a sole explanation for both types of peculiarity, and suggest that they may represent hitherto unrecognized tracers of composition and/or gravity. Clear trends in z′(AB) −J and Y−J are apparent for our sample, consistent with weakening absorption in the red wing of the K i line at 0.77 μm with decreasing effective temperature. We have used our sample to estimate space densities for T6–T9 dwarfs. By comparing our sample to Monte Carlo simulations of field T dwarfs for various mass functions of the form ψ(M) ∝ M−α pc−3 M−1⊙, we have placed weak constraints on the form of the field mass function. Our analysis suggests that the substellar mass function is declining at lower masses, with negative values of α preferred. This is at odds with results for young clusters that have been generally found to have α > 0.

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