Ring formation by tidal disruption of a passing body

Ryuki Hyodo (1) , Sébastien Charnoz (1) , Hidenori Genda , Keiji Ohtsuki

1 IPGP - Institut de Physique du Globe de Paris

The origin of rings around giant planets remains elusive. Here we investigate the tidal disruption of a passing object and the subsequent formation of planetary rings. First, we perform SPH simulations of the tidal destruction of differentiated objects with the mass of M~10²²kg 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. Therefore, in order to see their long-term evolution, we perform N-body simulations including the planet's oblateness up to J₄ starting with data obtained from the SPH simulations. Our N-body simulations show that the chunks are tidally destructed during their next several orbits and become collections of smaller particles. 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.

Domaines: Planète et Univers [physics]

Ryuki Hyodo, Sébastien Charnoz, Hidenori Genda, Keiji Ohtsuki. Ring formation by tidal disruption of a passing body. American Astronomical Society, 2016, à renseigner, Unknown Region. p. 196-207. ⟨insu-03581289⟩