A Search for L/T Transition Dwarfs with Pan-STARRS1 and WISE. III. Young L Dwarf Discoveries and Proper Motion Catalogs in Taurus and Scorpius-Centaurus
Abstract
We present the discovery of eight young M7-L2 dwarfs in the Taurus star-forming region and the Scorpius-Centaurus OB Association, serendipitously found during a wide-field search for L/T transition dwarfs using Pan-STARRS1 (optical) and WISE (mid-infrared) photometry. We identify PSO J060.3200+25.9644 (near-infrared spectral type L1) and PSO J077.1033+24.3809 (L2) as new members of Taurus based on their vl-g gravity classifications, the consistency of their photometry and proper motions with previously known Taurus objects, and the low probability of contamination by field objects. PSO J077.1033+24.3809 is the coolest substellar member of Taurus found to date. Both Taurus objects are among the lowest-mass free-floating objects ever discovered, with estimated masses ≈6 {M}{Jup}, and provide further evidence that isolated planetary-mass objects can form as part of normal star formation processes. PSO J060.3200+25.9644 (a.k.a. DANCe J040116.80+255752.2) was previously identified as a likely member of the Pleiades (age ≈ 125 {Myr}) based on photometry and astrometry, but its vl-g gravity classification and near-infrared photometry imply a much younger age and thus point to Taurus membership. We have also discovered six M7-L1 dwarfs in outlying regions of Scorpius-Centaurus with photometry, proper motions, and low-gravity spectral signatures consistent with membership. These objects have estimated masses ≈15-36 {M}{Jup}. The M7 dwarf, PSO J237.1470-23.1489, shows excess mid-infrared flux implying the presence of a circumstellar disk. Finally, we present catalogs of Pan-STARRS1 proper motions for low-mass members of Taurus and Upper Scorpius with median precisions of ≈3 mas yr-1, including 67 objects with no previous proper motion and 359 measurements that improve on literature values.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 2017
- DOI:
- arXiv:
- arXiv:1702.00789
- Bibcode:
- 2017ApJ...837...95B
- Keywords:
-
- brown dwarfs;
- proper motions;
- stars: formation;
- stars: individual: PSO J060.3200+25.9644;
- PSO J077.1033+24.3809;
- PSO J237.1470‑23.1489;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- ApJ, in press. No change to the preprint. Electronic tables available at http://www.ifa.hawaii.edu/~wbest/Will_Best/Taurus_Sco_Catalogs.html
