Ring Formation around Giant Planets by Tidal Disruption of a Single Passing Large Kuiper Belt Object

Abstract

The origin of rings around giant planets remains elusive. Saturn's rings are massive and made of 90-95% of water ice. In contrast, the much less massive rings of Uranus and Neptune are dark and likely to have higher rock fraction. Here we investigate, for the first time, the tidal disruption of a passing object, including the subsequent formation of planetary rings. First, we perform SPH simulations of the tidal destruction of big differentiated objects ($M_{\mathrm{body}}=10^{21-23}$) that experience close encounters with Saturn or Uranus. We find that about $0.1-10$% of the mass of the passing body is gravitationally captured around the planet. However, these fragments are initially big chunks and have highly eccentric orbits around the planet. Then, we perform N-body simulations including the planet's oblateness, starting with data obtained from the SPH simulations. Our N-body simulations show that the chunks are tidally destroyed during their next several orbits. Their individual orbits then start to precess incoherently around the planet's equator, which enhances their encounter velocities on longer-term evolution, resulting in more destructive impacts. These collisions would damp their eccentricities resulting in a progressive collapse of the debris cloud into a thin equatorial and low-eccentricity ring. These high energy impacts are expected to be catastrophic enough to produce small particles. Our numerical results also show that the mass of formed rings is large enough to explain current rings including inner regular satellites around Saturn and Uranus. In the case of Uranus, a body can go deeper inside the planet's Roche limit resulting in a more efficient capture of rocky material compared to Saturn's case in which mostly ice is captured. Thus, our results can naturally explain the compositional difference between the rings of Saturn, Uranus and Neptune.

33 pages, 21 figures; accepted in Icarus

References in corpus (7)

• Origin of the Structure of the Kuiper Belt during a Dynamical Instability in the Orbits of Uranus and Neptune
• Formation of Regular Satellites from Ancient Massive Rings in the Solar System
• Did Saturn's rings form during the Late Heavy Bombardment ?
• Rotational properties of the binary and non-binary populations in the Trans-Neptunian belt
• Formation of Multiple-Satellite Systems From Low-Mass Circumplanetary Particle Disks
• Origin of Europa and the Galilean Satellites
• Formation of Jupiter and Conditions for Accretion of the Galilean Satellites

Cited by in corpus (8)

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• Tidal disruption of planetary bodies by white dwarfs I: A hybrid SPH-analytical approach
• Accretion of Saturn's Inner Mid-sized Moons from a Massive Primordial Ice Ring
• Early formation of moons around large trans-Neptunian objects via giant impacts
• The search for disks or planetary objects around directly imaged companions: A candidate around DH Tau B
• On the Impact Origin of Phobos and Deimos II: True Polar Wander and Disk Evolution
• A Pluto--Charon Sonata: Dynamical Limits on the Masses of the Small Satellites
• Mean Motion Resonances With Nearby Moons: An Unlikely Origin For The Gaps Observed In The Ring Around The Exoplanet J1407b