The First AllWISE Proper Motion Discovery: WISEA J070720.50+170532.7

Abstract

While quality checking a new motion-aware co-addition of all 12.5 months of WISE data, the source WISE J070720.48+170533.0 was found to have moved 0.9 arc-sec in 6 months. Backtracking this motion allowed us to identify this source as 2MASS J07071961+1705464 and with several entries in the USNO B catalog. An astrometric fit to these archival data gives a proper motion of 1793 +/- 2 mas/yr and a parallax of 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 4.36E-11 radians. No clear evidence of H_2 collision-induced absorption is seen in the near-IR. 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 about -21 +/- 18 km/sec relative to the Sun. Given its apparent magnitude, the distance is about 39 +/- 9 pc and the tangential velocity is probably about 330 km/sec, but a more precise parallax is needed to be certain.

Accepted by the Astronomical Journal, 10 pages LaTex with 9 embedded figures. UCAC and CMC data added, fits updated

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Cited by in corpus (7)

• Discovery of a ~250 K Brown Dwarf at 2 pc from the Sun
• The AllWISE Motion Survey and The Quest for Cold Subdwarfs
• Characterization of High Proper Motion Objects from the Wide-field Infrared Survey Explorer
• The Solar Neighborhood XLII. Parallax Results from the CTIOPI 0.9-m Program --- Identifying New Nearby Subdwarfs Using Tangential Velocities and Locations on the H-R Diagram
• An ancient F-type subdwarf from the halo crossing the Galactic plane
• WISEA J064750.85-154616.4: a new nearby L/T transition dwarf
• Accretion and OH Photodissociation at a Nearby T Tauri System in the beta Pictoris Moving Group