The Young Substellar Companion ROXs 12 B: Near-infrared Spectrum, System Architecture, and Spin–Orbit Misalignment
- McDonald Observatory and the Department of Astronomy, University of Texas at Austin, Austin, TX 78712 (United States)
- California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA 91125 (United States)
- Center for Astrophysics and Space Astronomy, University of Colorado at Boulder, Boulder, CO 80309 (United States)
- Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)
- Institute for Astronomy, University of Hawai‘i at Mānoa, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
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 {sub 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{sub −2}{sup +4} Myr) imply a mass of 17.5 ± 1.5 M {sub 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 {sub *} 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{sub −11}{sup +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.
- OSTI ID:
- 22863018
- Journal Information:
- The Astronomical Journal (Online), Vol. 154, Issue 4; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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