The planetesimal bow shock model for chondrule formation A more quantitative assessment of the standard (fixed Jupiter) case

One transient heating mechanism that can potentially explain the formation of most meteoritic chondrules 1-3Myr after CAIs is shock waves produced by planetary embryos perturbed into eccentric orbits via resonances with Jupiter following its formationThe mechanism includes both bow shocks upstream of resonant bodies and impact vapor plume shocks produced by high-velocity collisions of the embryos with small nonresonant planetesimalsHere, we investigate the efficiency of both shock processes using an improved planetesimal accretion and orbital evolution code together with previous simulations of vapor plume expansion in the nebulaOnly the standard version of the model (with Jupiter assumed to have its present semimajor axis and eccentricity) is consideredAfter several hundred thousand years of integration time, about 4-5% of remaining embryos have eccentricities greater than about 0.33 and shock velocities at 3AU exceeding 6kms^-1, currently considered to be a minimum for melting submillimeter-sized silicate precursors in bow shocksMost embryos perturbed into highly eccentric orbits are relatively large-half as large as the Moon or largerBodies of this size could yield chondrule-cooling rates during bow shock passage compatible with furnace experiment resultsThe cumulative area of the midplane that would be traversed by highly eccentric embryos and their associated bow shocks over a period of 1-2Myr is <1% of the total areaHowever, future simulations that consider a radially migrating Jupiter and alternate initial distributions of the planetesimal swarm may yield higher efficiencies.