New Jupiter Satellites and Moon-Moon Collisions

TL;DR

This paper reports the discovery of 12 new Jupiter satellites, including an unusual prograde satellite with a unique orbit, and suggests that moon-moon collisions have occurred in Jupiter's satellite system over solar system history.

Contribution

The discovery of 12 new Jupiter satellites, including the unique orbit of S/2016 J2, and analysis of their stability and collision history.

Findings

12 new satellites discovered around Jupiter.

S/2016 J2 has an unprecedented orbit among outer satellites.

Prograde-retrograde moon-moon collisions likely occurred in Jupiter's history.

Abstract

We report the discovery of 12 new satellites of Jupiter, giving Jupiter 79 known satellites. The new finds are between 23rd-24th mag in the r-band and 1-3 km in diameter assuming dark albedos. Nine of the discoveries are in the distant retrograde satellite groupings. Two of the new satellites are in the closer Himalia prograde group near 28 degrees in inclination. S/2016 J2, nicknamed Valetudo, has an orbit unlike any other known outer satellite and is the most distant prograde satellite around any planet at 0.36 Hill radii. Numerical simulations show S/2016 J2 is very stable, with average and range of i=34.2+-3 deg, e=0.216+-0.125, and a=18.9+-0.7 million km over 100 Myrs. Our stability simulations show a S/2016 J2 like orbit would be stable out to a=21.8 million km or 0.41 Hill radii, but no further, unlike more distant and eccentric retrograde satellites. S/2016 J2's large semi-major axis means it significantly overlaps the orbits of the distant retrogrades. A prograde-retrograde moon-moon collision between outer satellites of Jupiter has likely happened over the age of the solar system.