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SUMMARY:A narrowly missed four-body resonant chain among the Galilean moon
 s
DTSTART:20261112T133000Z
DTEND:20261112T143000Z
DTSTAMP:20261107T205300Z
UID:indico-event-3428@indico.obspm.fr
DESCRIPTION:The Galilean moons of Jupiter present one of the most peculiar
  orbital configurations in the solar system: a 4:2:1 three-body resonance 
 between Io\, Europa\, and Ganymede\, known as Laplace resonance. The outer
  moon\, Callisto\, is not involved in the Laplace resonance\, but it is cu
 rrently very close to a 7:3 resonance with Ganymede. Considering the estim
 ated rate of the moons' orbital migration\, this 7:3 resonance was encount
 ered approximately two million years ago. To assess the effect of this re
 sonance crossing\, we performed accurate numerical simulations of the moon
 s' orbital evolution over the last few million years. We found that the dy
 namical pathway that best reproduces the current configuration of the syst
 em requires that Ganymede and Callisto were not captured into the 7:3 reso
 nance\, not even temporarily. In this scenario\, the moons started with ec
 centricities slightly larger than today's\, which decreased due to the res
 onance crossing\, eventually matching their present-day values. Under diff
 erent initial conditions\, capture into the 7:3 resonance would have been 
 almost unavoidable\, and today we could admire a four-body resonant chain 
 between the Galilean satellites. However\, had the moons been captured and
  subsequently exited the resonance\, their eccentricities would have incre
 ased far too large\, making such an evolutionary path incompatible with th
 e observed system. Nevertheless\, the crossing of the 7:3 resonance expla
 ins orbital features that have remained a mystery until now\, such as the 
 libration amplitude of the Laplace resonance. Moreover\, we found evidence
  of a three-body resonance crossing among the three outer moons that occur
 red just 20\,000 years ago.\n\nhttps://indico.obspm.fr/event/3428/
LOCATION:Allée des ateliers/0-1 - Danjon (PARIS)
URL:https://indico.obspm.fr/event/3428/
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