Accretion of the gaseous envelope of Jupiter around a 5-10 Earth-mass core

New numerical simulations of the formation and evolution of Jupiter are presented. The formation model assumes that first a solid core of several M circle plus accretes from the planetesimals in the protoplanetary disk, and then the core captures a massive gaseous envelope from the protoplanetary disk. Earlier studies of the core accretion-gas capture model [Pollack, J.B., Hubickyj, O., Bodenheimer, P., Lissauer, J.J., Podolak, M., Greenzweig, Y., 1996. Icarus 124, 62-85] demonstrated that it was possible for Jupiter to accrete with a solid core of 10-30 M circle plus in a total formation time comparable to the observed lifetime of protoplanetary disks. Recent interior models of Jupiter and Saturn that agree with all observational constraints suggest that Jupiter's core mass is 0-11 M circle plus and Saturn's is 9-22 M circle plus [Saumon, G., Guillot, T., 2004. Astrophys. J. 609, 1170-1180]. We have computed simulatons of the growth of Jupiter using various values for the opacity produced by grains in the protoplanet's atmosphere and for the initial planetesimal Surface density, sigma(init,Z), in the protoplanetary disk. We also explore the implications of halting the solid accretion at selected core mass values during the protoplanet's growth. Halting planetesimal accretion at low core mass Simulates the presence of a competing embryo, and decreasing the atmospheric opacity adjusting due to grains emulates the settling and coagulation of grains within the protoplanet's atmosphere. We examine the effects of ad these parameters to determine whether or not gas runaway can occur for small mass cores on a reasonable timescale. We compute four series Of Simulations with the latest version Of our code, which contains updated equation of state and opacity tables as well as other improvernents. Each series consists of a RIII without a cutoff in planetesimal accretion, plus up to three runs with a Cutoff at a particular core mass. The first series of runs is computed with an atmospheric opacity due to grains (hereafter referred to as 'grain opacity') that is 2% of the interstellar value and sigma(init),(Z) = 10 g/cm(2). Cutoff runs are computed for core masses of 10, 5, and 3 M circle plus. The second series of Jupiter models is computed with the grain opacity at the full interstellar Value and sigma(init,Z) = 10 g-/cm(2). Cutoff runs are computed for core masses of 10 and 5 M circle plus. The third series of runs is computed with the grain opacity at 2% of the interstellar value and sigma(init,Z) = 6 g/cm(2). One cutoff run is computed with core mass of 5 M circle plus. The final series consists of one run, without a Cutoff, which is computed with a temperature dependent grain opacity (i.e., 2% of the interstellar value for T < 350 K ramping LIP to the full interstellar value for T > 500 K) and sigma(init,Z) = 10 g/cm(2.) Our results demonstrate that reducing grain opacities results in formation times less than half of those for models computed with full interstellar grain opacity values. The reduction of opacity due to grains in the upper portion of the envelope with T < 500 K has the largest effect on the lowering of the formation time. If the accretion of planetesimals is not cut off prior to the accretion of gas, then decreasing the surface density of planetesimals lowers the final core mass of the protoplanet, but increases the formation timescale considerably. Finally, a core mass cutoff results in a reduction of the time needed for I protoplanet to evolve to thestage of runaway gas accretion, provided the cutoff mass is sufficiently large. The overall results indicate that, with reasonable parameters, it is possible that Jupiter formed at 5 AU via the core accretion process in I Myr with a core of 10 M circle plus or in 5 Myr with a core of 5 M circle plus. Published by Elsevier Inc.