A dense ring of the trans-Neptunian object Quaoar outside its Roche limit

Area of Science:

• Planetary Science
• Astronomy
• Astrophysics

Background:

• Planetary rings are known around giant planets and some small bodies like Chariklo and Haumea.
• Previously, all dense rings were observed within the Roche limit, where tidal forces prevent satellite formation.
• The Roche limit is a theoretical boundary defining where celestial bodies held together by their own gravity will disintegrate due to a second celestial body's tidal forces.

Purpose of the Study:

• To report the discovery and characteristics of a ring system around the trans-Neptunian object (50000) Quaoar.
• To investigate the survival of ring material outside the classical Roche limit.
• To explore the mechanisms responsible for confining rings around small bodies.

Main Methods:

• Observations of the trans-Neptunian object (50000) Quaoar.
• Analysis of ring system location relative to Quaoar's Roche limit.
• Local collisional simulations using parameters derived from laboratory experiments.

Main Results:

• An inhomogeneous ring was detected orbiting (50000) Quaoar at 7.4 Quaoar radii.
• This ring is located well outside Quaoar's classical Roche limit.
• The ring orbits near the 1/3 spin-orbit resonance with Quaoar, a feature also observed in rings around Chariklo and Haumea.

Conclusions:

• The Roche limit may not be an absolute boundary for the survival of planetary ring material.
• Elastic collisions can play a crucial role in maintaining rings far from their parent bodies.
• Spin-orbit resonances appear to be significant in confining rings around small celestial bodies.