paper

Three Wide Planetary-Mass Companions to FW Tau, ROXs 12, and ROXs 42B

arXiv:1311.7664 · doi:10.1088/0004-637X/781/1/20

Abstract

We report the discovery of three planetary-mass companions (M = 6--20 ) in wide orbits ( 150--300 AU) around the young stars FW Tau (Taurus-Auriga), ROXs 12 (Ophiuchus), and ROXs 42B (Ophiuchus). All three wide planetary-mass companions ("PMCs") were reported as candidate companions in previous binary survey programs, but then were neglected for 10 years. We therefore obtained followup observations which demonstrate that each candidate is comoving with its host star. Based on the absolute magnitudes, we infer masses (from hot-start evolutionary models) and projected separations of 10 4 and 330 30 AU for FW Tau b, 16 4 and 210 20 AU for ROXs 12 b, and 10 4 and 140 10 AU for ROXs 42B b. We also present similar observations for ten other candidates which show that they are unassociated field stars, as well as multicolor JHK'L' near-infrared photometry for our new PMCs and for five previously-identified substellar or planetary-mass companions. The NIR photometry for our sample of eight known and new companions generally parallels the properties of free-floating low-mass brown dwarfs in these star-forming regions. However, 5 of the 7 objects with M 30 are redder in K'-L' than the distribution of young free-floating counterparts of similar J-K'. We speculate that this distinction could indicate a structural difference in circum-planetary disks, perhaps tied to higher disk mass since at least two of the objects in our sample are known to be accreting more vigorously than typical free-floating counterparts.

Accepted to ApJ; 17 pages, 10 figures, 4 tables in emulateapj format. Replaced to update acknowledgements, reduce usage of MathJAX in abstract, and add a note in proof

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