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 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.
- Publication:
-
The Astronomical Journal
- Pub Date:
- March 2014
- DOI:
- 10.1088/0004-6256/147/3/61
- arXiv:
- arXiv:1310.6717
- Bibcode:
- 2014AJ....147...61W
- Keywords:
-
- brown dwarfs;
- infrared: stars;
- solar neighborhood;
- stars: individual: WISEA J070720.50+170532.7;
- stars: late-type;
- stars: low-mass;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- Accepted by the Astronomical Journal, 10 pages LaTex with 9 embedded figures. UCAC and CMC data added, fits updated