Planetary Spin and Obliquity from Mergers

Abstract

In planetary systems with sufficiently small inter-planet spacing, close encounters can lead to planetary collisions/mergers or ejections. We study the spin property of the merger products of two giant planets in a statistical manner using numerical simulations and analytical modeling. Planetary collisions lead to rapidly rotating objects and a broad range of obliquities. We find that, under typical conditions for two-planet scatterings, the distributions of spin magnitude $S$ and obliquity ${\Theta }_{\mathrm{SL}}$ of the merger products have simple analytical forms: $f_S\propto S$ and $f_{\cos {\Theta }_{\mathrm{SL}}}\propto (1-{\cos }^2{\Theta }_{\mathrm{SL}}{)}^{-1/2}$. Though parameter studies, we determine the regime of validity for the analytical distributions of spin and obliquity. Since planetary mergers is a major outcome of planet-planet scatterings, observational search for the spin/obliquity signatures of exoplanets would provide important constraints on the dynamical history of planetary systems.

References in corpus (22)

• The NumPy array: a structure for efficient numerical computation
• REBOUND: An open-source multi-purpose N-body code for collisional dynamics
• Dynamical Outcomes of Planet-Planet Scattering
• IAS15: A fast, adaptive, high-order integrator for gravitational dynamics, accurate to machine precision over a billion orbits
• Dynamical Origin of Extrasolar Planet Eccentricity Distribution
• Origins of Eccentric Extrasolar Planets: Testing the Planet-Planet Scattering Model
• The fast spin-rotation of a young extrasolar planet
• Collisions between Gravity-Dominated Bodies: 2. The Diversity of Impact Outcomes during the End Stage of Planet Formation
• Collisions Between Gravity-Dominated Bodies: 1. Outcome Regimes and Scaling Laws
• Dynamical Instabilities in Extrasolar Planetary Systems Containing Two Giant Planets
• Measuring the Oblateness and Rotation of Transiting Extrasolar Giant Planets
• Migration and Dynamical Relaxation in Crowded Systems of Giant Planets
• Constraining the Rotation Rate of Transiting Extrasolar Planets by Oblateness Measurements
• Scattering outcomes of close-in planets: constraints on planet migration
• NOTE: Explaining why the Uranian satellites have equatorial prograde orbits despite the large planetary obliquity
• On the Terminal Rotation Rates of Giant Planets
• Obliquity Constraints on an Extrasolar Planetary-Mass Companion
• In-Situ Scattering of Warm Jupiters and Implications for Dynamical Histories
• Inferring Planetary Obliquity Using Rotational & Orbital Photometry
• Excitation of Planetary Obliquities Through Planet-Disk Interactions
• Tilting Ice Giants with a Spin-Orbit Resonance
• Breaking the centrifugal barrier to giant planet contraction by magnetic disc braking

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• Long-term Evolution of Tightly-Packed Stellar Black Holes in AGN Disks: Formation of Merging Black-Hole Binaries via Close Encounters
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• Giant Planet Scatterings and Collisions: Hydrodynamics, Merger-Ejection Branching Ratio, and Properties of the Remnants
• Dynamics of Colombo's Top: Tidal Dissipation and Resonance Capture, With Applications to Oblique Super-Earths, Ultra-Short-Period Planets and Inspiraling Hot Jupiters
• Primordial Obliquities of Brown Dwarfs and Super-Jupiters from Fragmenting Gravito-Turbulent Discs
• Superhabitability of High-Obliquity and High-Eccentricity Planets
• Non-Trivial Oblique Spin Equilibria of Super-Earths in Multi-planetary Systems
• Leaning Sideways: VHS 1256-1257 b is a Super-Jupiter with a Uranus-like Obliquity
• Tilting Planets During Planet Scattering
• Detecting Planetary Oblateness in the Era of JWST: A Case Study of Kepler-167e
• Constraining the oblateness of transiting planets with photometry and spectroscopy
• Future destabilisation of Titan as a result of Saturn's tilting
• Warm Jupiters Beyond the Tidal Synchronization Limit May Exhibit a Wide Range of Secondary Eclipse Depths
• An extremely low-density exoplanet spins slow
• Multiverse Predictions for Habitability: Planetary Characteristics
• Spin Dynamics of Extrasolar Giant Planets in Planet-Planet Scattering
• Planetary Obliquity Excitation Through Pre-Main Sequence Stellar Evolution