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arXiv · 1401.5982

The discovery of a T6.5 subdwarf

Ben Burningham·L. Smith·C. V. Cardoso·P. W. Lucas·A. J. Burgasser·H. R. A. Jones·R. L. Smart
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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.

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Ben Burningham, L. Smith, C. V. Cardoso, P. W. Lucas, A. J. Burgasser, H. R. A. Jones, R. L. Smart. 2014-01-23. The discovery of a T6.5 subdwarf. https://doi.org/10.1093/mnras%2Fstu184

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