The Nice model can explain the dispersion of the prograde Himalia family of irregular satellites at Jupiter
Abstract
More than 50 irregular satellites revolve around Jupiter in which at least three distinct collisional families are identified. Among them, the Himalia family is unique in the large velocity dispersion--several hundred m/s--among its members, inconsistent with a purely collisional origin.We explore this puzzle in the context of the Nice scenario of early solar system evolution. There, the giant planets migrated significant distances due to interactions with a primordial planetesimal disk. We generate a synthetic, collisionally-produced Himalia family and follow its evolution through principal events of the Nice model. Two situations are considered: (i) The planetesimal disk is solely composed of large, moon-sized objects. In this case, the family is dramatically scattered, especially in semimajor axis and eccentricity, as the planetesimals fly by Jupiter. The velocity dispersion of $\sim60\%$ of family members is raised to several hundred m/s, satisfactorily explaining the observed dispersion. However, this situation is not likely as the considered planetesimals seem unphysically massive. We now consider the alternative case (ii) within the so-called ``Jumping Jupiter’’ where planetary, rather than planetesimal encounters are responsible for the observed dispersion. Here, ice giants encounter Jupiter up to a few hundred times (Nesvorn\'{y} \& Morbidelli 2012). We find $\lesssim20$ such planetary encounters disperse the synthetic family to the observed degree. We also find that the family cannot survive $\sim100$ such fly-bys as the satellites become too widely dispersed.Reference: Nesvorn\'{y}, D., \& Morbidelli, A. 2012, AJ, 144, 117.
- Publication:
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AAS/Division for Planetary Sciences Meeting Abstracts #49
- Pub Date:
- October 2017
- Bibcode:
- 2017DPS....4951104L