Jupiter's Obliquity and a Long-lived Circumplanetary Disk

It has been claimed (Canup and Ward 2002; Ward 2003) that a long-lived massive (compared to the mass of the Galilean satellites) circumplanetary gas disk is inconsistent with Jupiter's low obliquity. Such a constraint could be downplayed on the basis that it deals with a single observation. Here we argue that this argument is flawed because it assumes a solar system much like that of the present day with the one exception of a circumjovian disk which is then allowed to dissipate on a long timescale (10^6-10^7 yrs). Given that the sequence of events in solar-system history that fit known constraints is non-unique, we choose for the sake of clarity of exposition the orbital architecture framework of Tsiganis et al. (2005), in which Jupiter and Saturn were once in closer, less inclined orbits than they are at present, and show that Jupiter's low obliquity is consistent with the SEMM (solids-enhanced minimum mass) satellite formation model of Mosqueira and Estrada (2003a,b).