The discovery of a T6.5 subdwarf. Issue 1 (8th March 2014)

• Record Type: Journal Article
• Authors: Burningham, Ben; Smith, L.; Cardoso, C. V.; Lucas, P. W.; Burgasser, A. J.; Jones, H. R. A.; Smart, R. L.
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 440:Issue 1(2014)
• Page Start: 359
• Page End: 364
• Publication Date: 2014-03-08
• Subjects: surveys -- brown dwarfs -- stars: low-mass; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stu184
• Languages: English
• ISSNs: 0035-8711

Abstract

Abstract: We report the discovery of ULAS J131610.28+075553.0, an sdT6.5 dwarf in the UKIDSS Large Area Survey 2 epoch proper motion catalogue. This object displays significant spectral peculiarity, with the largest yet seen deviations from T6 and T7 templates in the Y and K bands for this subtype. Its large, ∼1 arcsec yr −1, proper motion suggests a large tangential velocity of V tan ≈ 240–340 km s −1, if we assume its M J lies within the typical range for T6.5 dwarfs. This makes it a candidate for membership of the Galactic halo population. However, other metal-poor T dwarfs exhibit significant under luminosity both in specific bands and bolometrically. As a result, it is likely that its velocity is somewhat smaller, and we conclude it is a likely thick disc or halo member. This object represents the only T dwarf earlier than T8 to be classified as a subdwarf, and is a significant addition to the currently small number of known unambiguously substellar subdwarfs.