Can the Uranian Satellites Form from a Debris Disk Generated by a Giant Impact?. (arXiv:1909.13065v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Ishizawa_Y/0/1/0/all/0/1">Yuya Ishizawa</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sasaki_T/0/1/0/all/0/1">Takanori Sasaki</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hosono_N/0/1/0/all/0/1">Natsuki Hosono</a>
Hydrodynamic simulations of a giant impact to proto-Uranus indicated that
such an impact could tilt its rotational axis and produce a circumplanetary
debris disk beyond the corotation radius of Uranus. However, whether Uranian
satellites can actually be formed from such a wide disk remains unclear.
Herein, we modeled a wide debris disk of solids with several initial conditions
inferred from the hydrodynamic simulations, and performed $N$-body simulations
to investigate in-situ satellite formation from the debris disk. We also took
account of orbital evolutions of satellites due to the planetary tides after
the growth of satellites. We found that, in any case, the orbital distribution
of the five major satellites could not be reproduced from the disk as long as
the power index of its surface density is similar to that of the disk generated
just after the giant impact: Satellites in the middle region obtained much
larger masses than Ariel or Umbriel, while the outermost satellite did not grow
to the mass of Oberon. Our results indicate that we should consider the thermal
and viscous evolution of the evaporated disk after the giant impact to form the
five major satellites through the in-situ formation scenario. On the other
hand, the small inner satellites would be formed from the rings produced by the
disrupted satellites which migrated from around the corotation radius of Uranus
due to the planetary tides.
Hydrodynamic simulations of a giant impact to proto-Uranus indicated that
such an impact could tilt its rotational axis and produce a circumplanetary
debris disk beyond the corotation radius of Uranus. However, whether Uranian
satellites can actually be formed from such a wide disk remains unclear.
Herein, we modeled a wide debris disk of solids with several initial conditions
inferred from the hydrodynamic simulations, and performed $N$-body simulations
to investigate in-situ satellite formation from the debris disk. We also took
account of orbital evolutions of satellites due to the planetary tides after
the growth of satellites. We found that, in any case, the orbital distribution
of the five major satellites could not be reproduced from the disk as long as
the power index of its surface density is similar to that of the disk generated
just after the giant impact: Satellites in the middle region obtained much
larger masses than Ariel or Umbriel, while the outermost satellite did not grow
to the mass of Oberon. Our results indicate that we should consider the thermal
and viscous evolution of the evaporated disk after the giant impact to form the
five major satellites through the in-situ formation scenario. On the other
hand, the small inner satellites would be formed from the rings produced by the
disrupted satellites which migrated from around the corotation radius of Uranus
due to the planetary tides.
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