Discovery of the benchmark metal poor T8 dwarf BD+01 2920B

Pinfield, D.J.; Burningham, B.; Lodieu, N.; Leggett, S.; Tinney, C.G.; van Spaandonk, L.; Marocco, F.; Smart, R.; Gomes, J.; Smith, Leigh; Lucas, P.W.; Day-jones, A.; Murray, D.; Katsiyannis, A. C.; Catalan, S.; Cardoso, C.; Clarke, James; Folkes, S.; Galvez-Ortiz, M.; Homeier, D.; Jenkins, J.; Jones, H.R.A.; Zhang, Z.

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Author

Pinfield, D.J.

Burningham, B.

Lodieu, N.

Leggett, S.

Tinney, C.G.

van Spaandonk, L.

Marocco, F.

Smart, R.

Gomes, J.

Smith, Leigh

Lucas, P.W.

Day-jones, A.

Murray, D.

Katsiyannis, A. C.

Catalan, S.

Cardoso, C.

Clarke, James

Folkes, S.

Galvez-Ortiz, M.

Homeier, D.

Jenkins, J.

Jones, H.R.A.

Zhang, Z.

Abstract

We have searched the Wide-field Infrared Survey Explorer first data release for widely separated (<=10,000AU) late T dwarf companions to Hipparcos and Gliese stars. We have discovered a new binary system containing a K-band suppressed T8p dwarf WISEP J142320.86+011638.1 and the mildly metal poor ([Fe/H]=-0.38+-0.06) primary BD+01 2920 (HIP 70319), a G1 dwarf at a distance of 17.2pc. This new benchmark has Teff=680+-55K and a mass of 20-50MJup. Its spectral properties are well modelled except for known discrepancies in the Y and K bands. Based on the well determined metallicity of its companion, the properties of BD+01 2920B imply that the currently known T dwarfs are dominated by young low-mass objects. We also present an accurate proper motion for the T8.5 dwarf WISEP J07003.84+272544.8