The discovery of a T6.5 subdwarf
Abstract
We report the discovery of ULAS J131610.28+075553.0, a 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, proper motion suggests a large tangential velocity of Vtan = 240 - 340km/s, 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.
Cite
@article{arxiv.1401.5982,
title = {The discovery of a T6.5 subdwarf},
author = {Ben Burningham and L. Smith and C. V. Cardoso and P. W. Lucas and A. J. Burgasser and H. R. A. Jones and R. L. Smart},
journal= {arXiv preprint arXiv:1401.5982},
year = {2015}
}
Comments
8 pages, 5 figures. MNRAS accepted