Obliquity Constraints on the Planetary-mass Companion HD 106906 b

Abstract

We constrain the angular momentum architecture of HD 106906, a 13 $\pm$ 2 Myr old system in the ScoCen complex composed of a compact central binary, a widely separated planetary-mass tertiary HD 106906 b, and a debris disk nested between the binary and tertiary orbital planes. We measure the orientations of three vectors: the companion spin axis, companion orbit normal, and disk normal. Using near-IR high-resolution spectra from Gemini/IGRINS, we obtain a projected rotational velocity of $v\sin i_p$ = 9.5 $\pm$ 0.2 km/s for HD 106906 b. This measurement together with a published photometric rotation period implies the companion is viewed nearly pole-on, with a line-of-sight spin axis inclination of $i_p$ = 14 $\pm$ 4 degrees or 166 $\pm$ 4 degrees. By contrast, the debris disk is known to be viewed nearly edge-on. The likely misalignment of all three vectors suggests HD 106906 b formed by gravitational instability in a turbulent environment, either in a disk or cloud setting.

accepted to AJ. 14 pages, 7 figures

References in corpus (23)

• Molecfit: A general tool for telluric absorption correction. I. Method and application to ESO instruments
• The Evolution of L and T Dwarfs in Color-Magnitude Diagrams
• Molecfit: A general tool for telluric absorption correction II. Quantitative evaluation on ESO-VLT X-Shooter spectra
• On the diversity and statistical properties of protostellar discs
• Population-Level Eccentricity Distributions of Imaged Exoplanets and Brown Dwarf Companions: Dynamical Evidence for Distinct Formation Channels
• orbitize!: A Comprehensive Orbit-fitting Software Package for the High-contrast Imaging Community
• The Kozai-Lidov Mechanism in Hydrodynamical Disks
• On the Inference of a Star's Inclination Angle from its Rotation Velocity and Projected Rotation Velocity
• The Turbulent Origin of Outflow and Spin Misalignment in Multiple Star Systems
• Obliquity-Driven Sculpting of Exoplanetary Systems
• The Viewing Geometry of Brown Dwarfs Influences Their Observed Colours and Variability Properties
• Chaotic Dynamics of Stellar Spin in Binaries and the Production of Misaligned Hot Jupiters
• Atmospheric Circulation of Brown Dwarfs: Jets, Vortices, and Time Variability
• HST Rotational Spectral Mapping of Two L-Type Brown Dwarfs: Variability In and Out of Water Bands Indicates High-Altitude Haze Layers
• TESS Observations of the Luhman 16AB Brown Dwarf System: Rotational Periods, Lightcurve Evolution, and Zonal Circulation
• Excitation of Planetary Obliquities Through Planet-Disk Interactions
• The Young Substellar Companion ROXs 12 B: Near-Infrared Spectrum, System Architecture, and Spin-Orbit Misalignment
• Cloud Atlas: High-Contrast Time-Resolved Observations of Planetary-Mass Companions
• First detection of orbital motion for HD 106906 b: A wide-separation exoplanet on a Planet Nine-like orbit
• Rotational Light Curves of Jupiter from UV to Mid-Infrared and Implications for Brown Dwarfs and Exoplanets
• A Near-coplanar Stellar Flyby of the Planet Host Star HD 106906
• The effect of Semi-Collisional Accretion on Planetary Spins
• High signal-to-noise spectral characterization of the planetary-mass object HD 106906 b

Cited by in corpus (7)

• Stellar obliquities in exoplanetary systems
• Peering into the Young Planetary System AB Pic. Atmosphere, Orbit, Obliquity & Second Planetary Candidate
• Non-Trivial Oblique Spin Equilibria of Super-Earths in Multi-planetary Systems
• The case of HD 106906 debris disc: A binary's revenge
• Direct imaging of exoplanets: Legacy and prospects
• Formation History of HD106906 and the Vertical Warping of Debris Disks by an External Inclined Companion
• Prograde spin-up during gravitational collapse