Understanding sub-stellar populations using wide-field infrared surveys

¹ Centre for Astrophysics Research, University of Hertfordshire, Hatfield AL10 9AB, UK
² Department of Astronomy, Universidad de Chile, Casilla 36-D, Santiago, Chile
³ Gemini Observatory, 670 N. A’ohoku Place, Hilo, HI 96720, USA
⁴ National Astronomical Observatory, Mitaka, Tokyo 181-8588, Japan
⁵ University of New South Wales, Sydney, NSW 2052, Australia
⁶ Institute for Astronomy, University of Hawai’i, 2680 Woodlawn Drive, Honolulu, HI 96822, USA
⁷ Georg-August-Universitat, Friedrich-Hund-Platz 1, 37077 Gottingen, Germany
⁸ Instituto de Astrofisica de Canarias, 38200 La Laguna, Spain
⁹ MIT Kavli Institute, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
¹⁰ Laboratorio de Astrofisica Estelar y Exoplanetas (LAEX), Spain
¹¹ Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ, UK
¹² Subaru Telescope, 650 North A’ohoku Place, Hilo, HI 96720, USA
¹³ Institute of Astronomy, Madingley Road, Cambridge CB3 0HA, UK

^a e-mail: D.J.Pinfield@herts.ac.uk

Abstract

This paper discusses benchmark brown dwarfs in various environments, and focuses on those in wide binary systems. We present a summary of the recently discovered T dwarf population from the UKIDSS Large Area Survey, and describe the constraints that it places on our knowledge of the sub-stellar initial mass function. We also present some exciting results from our ongoing search for wide companions to this sample, that has so far revealed an M4-T8.5 binary system at ∼12 parsecs and also the first ever Tdwarf-white dwarf binary system. The T dwarfs in these binaries have their properties constrained by the primary object and are thus benchmark objects that are already testing the predictions of theoretical model atmospheres.