The discovery of a T6.5 subdwarf
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 Vtan ≈ 240-340 km s-1, if we assume its MJ 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.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- May 2014
- DOI:
- 10.1093/mnras/stu184
- arXiv:
- arXiv:1401.5982
- Bibcode:
- 2014MNRAS.440..359B
- Keywords:
-
- surveys;
- brown dwarfs;
- stars: low-mass;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 8 pages, 5 figures. MNRAS accepted