Volume 518, July-August 2010Herschel: the first science highlights
|Number of page(s)||9|
|Section||Stellar structure and evolution|
|Published online||31 August 2010|
Extending the Canada-France brown dwarfs survey to the near-infrared: first ultracool brown dwarfs from CFBDSIR*
School of Physics & Astronomy,University of St Andrews
North Haugh, St Andrews KY16 9SS, UK e-mail: firstname.lastname@example.org
2 Université Joseph Fourier – Grenoble 1, Centre national de la recherche scientifique, Laboratoire d'Astrophysique de Grenoble (LAOG), UMR 5571, 38041 Grenoble Cedex 09, France
3 Canada-France-Hawaii Telescope Corporation, 65-1238 Mamalahoa Highway, Kamuela, HI96743, USA
4 Département de physique and Observatoire du Mont Mégantic, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montréal, QC H3C 3J7, Canada
5 Gemini Observatory Southern Operations Center c/o AURA, Casilla 603 La Serena, Chile
6 Observatoire de Besançon, Institut Utinam, UMR CNRS 6213, BP 1615, 25010 Besançon Cedex, France
7 Herzberg Institute of Astrophysics, National Research Council, 5071 West Saanich Rd, Victoria, BC V9E 2E7, Canada
8 Institut d'Astrophysique de Paris-CNRS, 98bis boulevard Arago, 75014 Paris, France
9 Oxford Astrophysics, Department of Physics, Denys Wilkinson Building Keble Road Oxford, OX1 3RH, UK
10 CRAL (UMR 5574 CNRS), École Normale Supérieure, 69364 Lyon Cedex 07, France
11 CEA-Saclay, IRFU, SAp, 91191 Gif-sur-Yvette, France
Accepted: 20 April 2010
Aims. We present the first results of the ongoing Canada-France Brown Dwarfs Survey-InfraRed, hereafter CFBDSIR, a near infrared extension to the optical wide-field survey CFBDS. Our final objectives are to constrain ultracool atmosphere physics by finding a statistically significant sample of objects cooler than 650 K and to explore the ultracool brown dwarf mass function building on a well-defined sample of such objects.
Methods. We identify candidates in CFHT/WIRCam J and CFHT/MegaCam z' images using optimised psf-fitting, and follow them up with pointed, near-infrared imaging with SOFI at the NTT. We finally obtain low-resolution spectroscopy of the coolest candidates to characterise their atmospheric physics.
Results. We have so far analysed and followed up all candidates on the first 66 square degrees of the 335 square degree survey. We identified 55 T-dwarfs candidates with and have confirmed six of them as T-dwarfs, including 3 that are strong later-than-T8 candidates, based on their far-red and NIR colours. We also present here the NIR spectra of one of these ultracool dwarfs, CFBDSIR1458+1013, which confirms it as one of the coolest brown dwarf known, possibly in the 550–600 K temperature range.
Conclusions. From the completed survey we expect to discover 10 to 15 dwarfs later than T8, more than doubling the known number of such objects. This will enable detailed studies of their extreme atmospheric properties and provide a stronger statistical basis for studies of their luminosity function.
Key words: methods: observational / brown dwarfs / techniques: photometric / techniques: spectroscopic / methods: data analysis
Based on observations obtained with WIRCam, a joint project of CFHT, Taiwan, Korea, Canada, France, and the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institute National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at TERAPIX and the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS. Based on observations made with the ESO New Technology Telescope at the La Silla Observatory under programs ID 082.C-0506(A) and 083.C-0797(A) with SOFI at NTT and ESO VLT Director Discretionary Time program 282.C-5075 with ISAAC.
© ESO, 2010
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