lissauer_core_accretion

lissauer_core_accretion - January 4, 2009 Preprint typeset...

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Unformatted text preview: January 4, 2009 Preprint typeset using L A T E X style emulateapj v. 03/07/07 MODELS OF JUPITERS GROWTH INCORPORATING THERMAL AND HYDRODYNAMIC CONSTRAINTS Jack J. Lissauer, Olenka Hubickyj 1 , Gennaro DAngelo 2 NASA Ames Research Center, Space Science and Astrobiology Division, MS 245-3, Moffett Field, CA 94035, USA and Peter Bodenheimer UCO/Lick Observatory, Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064, USA January 4, 2009 ABSTRACT We model the growth of Jupiter via core nucleated accretion, applying constraints from hydrody- namical processes that result from the diskplanet interaction. We compute the planets internal structure using a well tested planetary formation code that is based upon a Henyey-type stellar evolution code. The planets interactions with the protoplanetary disk are calculated using 3-D hy- drodynamic simulations. Previous models of Jupiters growth have taken the radius of the planet to be approximately one Hill sphere radius, R H . However, 3-D hydrodynamic simulations show that only gas within . 25 R H remains bound to the planet, with the more distant gas eventually participating in the shear flow of the protoplanetary disk. Therefore in our new simulations, the planets outer boundary is placed at the location where gas has the thermal energy to reach the portion of the flow not bound to the planet. We find that the smaller radius increases the time required for planetary growth by 5%. Thermal pressure limits the rate at which a planet less than a few dozen times as massive as Earth can accumulate gas from the protoplanetary disk, whereas hydrodynamics regulates the growth rate for more massive planets. Within a moderately viscous disk, the accretion rate peaks when the planets mass is about equal to the mass of Saturn. In a less viscous disk hydrodynamical limits to accretion are smaller, and the accretion rate peaks at lower mass. Observations suggest that the typical lifetime of massive disks around young stellar objects is 3Myr. To account for the dissipation of such disks, we perform some of our simulations of Jupiters growth within a disk whose surface gas density decreases on this timescale. In all of the cases that we simulate, the planets effective radiating temperature rises to well above 1000K soon after hydrodynamic limits begin to control the rate of gas accretion and the planets distended envelope begins to contract. According to our simulations, proto-Jupiters distended and thermally-supported envelope was too small to capture the planets current retinue of irregular satellites as advocated by Pollack et al. [Pollack, J.B., Burns, J.A., Tauber, M.E., 1979. Icarus 37, 587611]....
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This note was uploaded on 01/03/2012 for the course GEL 133 taught by Professor List during the Fall '10 term at Caltech.

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lissauer_core_accretion - January 4, 2009 Preprint typeset...

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