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Published October 2017 | Submitted + Published
Journal Article Open

The Young Substellar Companion ROXs 12 B: Near-infrared Spectrum, System Architecture, and Spin–Orbit Misalignment


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 M_(Jup) 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^(+4)_(-2) Myr) imply a mass of 17.5 ± 1.5 M_(Jup) 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^(+7)_(-11)°. 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.

Additional Information

© 2017 The American Astronomical Society. Received 2017 June 30; revised 2017 August 21; accepted 2017 August 24; published 2017 September 28. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The observatory was made possible by the generous financial support of the W. M. Keck Foundation. We thank the anonymous referee for constructive comments; we thank Trent Dupuy and Konstantin Batygin for helpful discussions about spin–orbit misalignments; Eric Nielsen and Sarah Blunt for the published posterior orbital inclination distribution of ROXs 12 B; and the Keck and Gemini Observatory staff for their exceptional support. Support for this work was provided by the National Aeronautics and Space Administration (NASA) through Hubble Fellowship grants HST-HF2-51369.001-A and HST-HF2-51336.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc. (AURA), for NASA, under contract NAS5-26555. H.A.K. acknowledges support from the Sloan Foundation. M.C.L. acknowledges support from National Science Foundation (NSF) grant NSF-AST-1518339. A.V. is supported by the NSF Graduate Research Fellowship, grant No. DGE 1144152. L.A.C. acknowledges grant support from CONICYT-FONDECYT number 1171246. This paper includes data taken at the McDonald Observatory of the University of Texas at Austin. It is also based on observations with the Mayall/RC-Spec spectrograph carried out through NOAO Prop. ID 2014A-0019. Based on observations obtained at the Gemini Observatory (NOAO Prop. ID: 2016A-0112; Gemini Program ID: GN-2016A-Q-37; PI: B Bowler; processed using the Gemini NIFS IRAF package), which is operated by AURA under a cooperative agreement with the NSF on behalf of the Gemini partnership: the NSF (United States); the National Research Council (Canada); CONICYT (Chile); Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina); and Ministério da Ciência, Tecnologia e Inovação (Brazil). IRAF is distributed by the National Optical Astronomy Observatory, which is operated by AURA under a cooperative agreement with the NSF. We utilized data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by NASA and the NSF. NASA's Astrophysics Data System Bibliographic Services, together with the VizieR catalog access tool and SIMBAD database operated at CDS, Strasbourg, France, were invaluable resources for this work. This paper includes data collected by the Kepler mission. Funding for the Kepler mission is provided by the NASA Science Mission directorate. This work used the Immersion Grating Infrared Spectrometer (IGRINS) that was developed under a collaboration between the University of Texas at Austin and the Korea Astronomy and Space Science Institute (KASI) with the financial support of the US National Science Foundation under grant AST-1229522 to the University of Texas at Austin and of the Korean GMT Project of KASI. This publication makes use of data products from the Wide-field 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 NASA. Finally, mahalo nui loa to the kama'āina of Hawai'i for their support of Keck and the Maunakea observatories. We are grateful to conduct observations from this mountain. Facilities: Keck:II (NIRC2) - KECK II Telescope, Keck:I (OSIRIS, HIRES) - , Smith (IGRINS) - McDonald Observatory's 2.7m Harlan J. Smith Telescope, Gemini:Gillett (NIFS) - Gillett Gemini North Telescope, Mayall (RC-Spec) - Kitt Peak National Observatory's 4 meter Mayall Telescope, Kepler - The Kepler Mission, IRTF (SpeX) - Infrared Telescope Facility.

Attached Files

Published - Bowler_2017_AJ_154_165.pdf

Submitted - 1708.07611.pdf


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