Constraints on Planet Nine's Orbit and Sky Position within a Framework of Mean Motion Resonances

Abstract

A number of authors have proposed that the statistically significant orbital alignment of the most distant Kuiper Belt Objects (KBOs) is evidence of an as-yet undetected planet in the outer solar system, now referred to colloquially a "Planet Nine". Dynamical simulations by Batygin & Brown (2016) have provided constraints on the range of the planet's possible orbits and sky locations. We extend these investigations by exploring the suggestion of Malhotra et al. (2016) that Planet Nine is in small integer ratio mean-motion resonances (MMRs) with several of the most distant KBOs. We show that the observed KBO semi-major axes present a set of commensurabilities with an unseen planet at $\sim 654\mathrm{AU}$ ($P\sim 16,725\mathrm{yr}$) that has a greater than $98\%$ chance of stemming from a sequence of MMRs rather than from a random distribution. We describe and implement a Monte-Carlo optimization scheme that drives billion-year dynamical integrations of the outer solar system to pinpoint the orbital properties of perturbers that are capable of maintaining the KBOs' apsidal alignment. This optimization exercise suggests that the unseen planet is most consistently represented with mass, $m\sim 6-12M_{\oplus }$, semi-major axis, $a\sim 654\mathrm{AU}$, eccentricity, $e\sim 0.45$, inclination, $i\sim 30^{\circ }$, argument of periastron, $\omega \sim 150^{\circ }$, longitude of ascending node, $\Omega \sim 50^{\circ }$, and mean anomaly, $M\sim 180^{\circ }$. A range of sky locations relative to this fiducial ephemeris are possible. We find that the region $30^{\circ }\lesssim \mathrm{RA}\lesssim 50^{\circ }$, $-20^{\circ }\lesssim \mathrm{Dec}\lesssim 20^{\circ }$ is promising.

References in corpus (8)

• Extreme trans-Neptunian objects and the Kozai mechanism: signalling the presence of trans-Plutonian planets
• New Extreme Trans-Neptunian Objects: Towards a Super-Earth in the Outer Solar System
• Generation of Highly Inclined Trans-Neptunian Objects by Planet Nine
• Discovery of A New Retrograde Trans-Neptunian Object: Hint of A Common Orbital Plane for Low Semi-Major Axis, High Inclination TNOs and Centaurs
• Solar Obliquity Induced by Planet Nine
• The inclination of the planetary system relative to the solar equator may be explained by the presence of Planet 9
• Consequences of a Distant Massive Planet on the Large Semi-major Axis Trans-Neptunian Objects
• Solar Obliquity Induced by Planet Nine: Simple Calculation

Cited by in corpus (19)

• The Planet Nine Hypothesis
• The EXPRES Stellar Signals Project II. State of the Field in Disentangling Photospheric Velocities
• Numerical Solutions for the orbital motion of the Solar System over the Past 100 Myr: Limits and new results
• Dynamical Evolution Induced by Planet Nine
• OSSOS XV: Probing the Distant Solar System with Observed Scattering TNOs
• Evaluating the Dynamical Stability of Outer Solar System Objects in the Presence of Planet Nine
• Orbital precession in the distant solar system; further constraining the Planet Nine hypothesis with numerical simulations
• Hot exoplanetary atmospheres in 3D
• Circularizing Planet Nine through dynamical friction with an extended, cold planetesimal belt
• Binary stripping as a plausible origin of correlated pairs of extreme trans-Neptunian objects
• Stellar winds as a mechanism to tilt the spin axes of Sun-like stars
• Evidence for a possible bimodal distribution of the nodal distances of the extreme trans-Neptunian objects: avoiding a trans-Plutonian planet or just plain bias?
• Outer Solar System Perihelion Gap Formation Through Interactions with a Hypothetical Distant Giant Planet
• A search for Planet 9 in the IRAS data
• A candidate location for Planet Nine from an interstellar meteoroid: The messenger hypothesis
• The Case for a Large-Scale Occultation Network
• A Search for Planet Nine with IRAS and AKARI Data
• A Far-Infrared Search for Planet Nine Using AKARI All-Sky Survey
• The orbit of Planet Nine