The discovery of the T8.5 dwarf UGPS J0521+3640

• Published in: Monthly notices of the Royal Astronomical Society. Letters 2011-06, Vol.414 (1), p.L90-L94
• Main Authors: Burningham, Ben, Lucas, P. W., Leggett, S. K., Smart, R., Baker, D., Pinfield, D. J., Tinney, C. G., Homeier, D., Allard, F., Zhang, Z. H., Gomes, J., Day-Jones, A. C., Jones, H. R. A., Kovács, G., Lodieu, N., Marocco, F., Murray, D. N., Sipőcz, B.
• Format: Article
• Language: English
• Subjects: brown dwarfs; stars: low-mass; surveys
• ISSN: 1745-3925; 1745-3933
• DOI: 10.1111/j.1745-3933.2011.01062.x

ABSTRACT We have carried out a search for late‐type T dwarfs in the UKIRT Infrared Deep Sky Survey Galactic Plane Survey 6th Data Release. The search yielded two persuasive candidates, both of which have been confirmed as T dwarfs. The brightest, UGPS J0521+3640, has been assigned the spectral type T8.5 and appears to lie at a distance of 7–9 pc. The fainter of the two, UGPS J0652+0324, is classified as a T5.5 dwarf and lies at an estimated distance of 28–37 pc. Warm‐Spitzer observations in IRAC channels 1 and 2, taken as part of the GLIMPSE360 Legacy Survey, are available for UGPS J0521+3640 and we used these data with the near‐infrared spectroscopy to estimate its properties. We find best‐fitting solar metallicity BT‐Settl models for Teff= 600 and 650 K and log g= 4.5 and 5.0. These parameters suggest a mass between 14 and 32MJ for an age between 1 and 5 Gyr. The proximity of this very cool T dwarf, and its location in the Galactic plane, makes it an ideal candidate for high‐resolution adaptive optics imaging to search for cool companions.