Astron. J., 154, 165-165 (2017/October-0)
The young substellar companion ROXs 12 B: near-infrared spectrum, system architecture, and spin-orbit misalignment.
BOWLER B.P., KRAUS A.L., BRYAN M.L., KNUTSON H.A., BROGI M., RIZZUTO A.C., MACE G.N., VANDERBURG A., LIU M.C., HILLENBRAND L.A. and CIEZA L.A.
Abstract (from CDS):
ROXs 12 (2MASS J16262803-2526477) is a young star hosting a directly imaged companion near the deuterium-burning limit. We present a suite of spectroscopic, imaging, and time-series observations to characterize the physical and environmental properties of this system. Moderate-resolution near-infrared spectroscopy of ROXs 12 B from Gemini-North/NIFS and Keck/OSIRIS reveals signatures of low surface gravity including weak alkali absorption lines and a triangular H-band pseudocontinuum shape. No signs of Paβ emission are evident. As a population, however, we find that about half (46% ± 14%) of young (<=15 Myr) companions with masses <=20 MJup possess actively accreting subdisks detected via Paβ line emission, which represents a lower limit on the prevalence of circumplanetary disks in general, as some are expected to be in a quiescent phase of accretion. The bolometric luminosity of the companion and age of the host star (6–2+4 Myr) imply a mass of 17.5 ± 1.5 MJup for ROXs 12 B based on hot-start evolutionary models. We identify a wide (5100 au) tertiary companion to this system, 2MASS J16262774-2527247, that is heavily accreting and exhibits stochastic variability in its K2 light curve. By combining v sin i* measurements with rotation periods from K2, we constrain the line-of-sight inclinations of ROXs 12 A and 2MASS J16262774-2527247 and find that they are misaligned by 60–11+7○. In addition, the orbital axis of ROXs 12 B is likely misaligned from the spin axis of its host star, ROXs 12 A, suggesting that ROXs 12 B formed akin to fragmenting binary stars or in an equatorial disk that was torqued by the wide stellar tertiary.
© 2017. The American Astronomical Society. All rights reserved.
brown dwarfs - planetary systems - planets and satellites: atmospheres - stars: individual: (ROXs 12, 2MASS J16262774-2527247) - stars: low-mass - stars: low-mass
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