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Published March 2014 | Published + Submitted
Journal Article Open

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


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 ω = 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 H_2 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.

Additional Information

© 2014 American Astronomical Society. Received 2013 October 23; accepted 2013 December 6; published 2014 February 10. We thank the referee, Ralf-Dieter Scholz, for a very fast and useful report pointing out the UCAC and CMC observations. This publication makes use of data products from the Widefield Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. The WISE, 2MASS, and USNO B data were all provided by the Infrared Science Archive at Caltech. The Digitized Sky Survey images were provided by the Space Telescope Science Institute. Support for M.F. was provided by NASA through Hubble Fellowship grant HF-51305.01-A. This research has benefitted from the SpeX Prism Spectral Libraries maintained by Adam Burgasser at http://www.browndwarfs.org/spexprism. Facilities: WISE, FMO:31in/FanCam, Hale (DoubleSpec), ARC (TSpec)

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Published - 1538-3881_147_3_61.pdf

Submitted - 1310.6717v2.pdf


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