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The first AllWISE proper motion discovery : WISEA J070720.50+170532.7.

Wright, E.L. and Kirkpatrick, J.D. and Gelino, C.R. and Fajardo-Acosta, S. and Mace, G. and Eisenhardt, P.R. and Stern, D. and McLean, I.S. and Skrutskie, M.F. and Oza, A. and Nelson, M.J. and Cushing, M.C. and Reid, I.N. and Fumagalli, M. and Burgasser, A.J. (2014) 'The first AllWISE proper motion discovery : WISEA J070720.50+170532.7.', Astronomical journal, 147 (3). p. 61.


While quality checking a new motion-aware co-addition of all 12.5 months of Wide-field Infrared Survey Explorer (WISE) data, we found that the source WISE J070720.48+170533.0 moved 0.''9 in six months. Backtracking this motion allowed us to identify this source as 2MASS J07071961+1705464, with several entries in the USNO B catalog. An astrometric fit to these archival data gives a proper motion of μ = 1793 ± 2 mas yr–1 and a parallax of piv = 35 ± 42 mas. Photometry from WISE, 2MASS, and the POSS can be fit reasonably well by a blackbody with T = 3658 K and an angular radius of 4.36 × 10–11 radians. No clear evidence of H2 collision-induced absorption is seen in the near-infrared. An optical spectrum shows broad deep CaH bands at 638 and 690 nm, broad deep Na D at 598.2 nm, and weak or absent TiO, indicating that this source is an ultra-subdwarf M star with a radial velocity v rad ≈ –21 ± 18 km s–1 relative to the Sun. Given its apparent magnitude, the distance is about 39 ± 9 pc and the tangential velocity is probably ≈330 km s–1, but a more precise parallax is needed to be certain.

Item Type:Article
Keywords:Brown dwarfs, Infrared: stars, Solar neighborhood, Stars: individual (WISEA J070720.50+170532.7), Stars: late-type, Stars: low-mass.
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Publisher statement:© 2014. The American Astronomical Society. All rights reserved.
Date accepted:No date available
Date deposited:08 September 2014
Date of first online publication:February 2014
Date first made open access:No date available

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