Hybrid Mechanisms for Gas/Ice Giant Planet Formation

Abstract

The effects of gas pressure gradients on the motion of solid grains in the solar nebula substantially enhances the efficiency of forming protoplanetary cores in the standard core accretion model in 'hybrid' scenarios for gas/ice giant planet formation. Such a scenario is enhanced core accretion which results from Epstein-drag induced inward radial migration of mm-sized grains and subsequent particle subdisk gravitational instability needed to build up a population of 1 km planetesimals. Solid/gas ratios can be enhanced by nearly $\sim 10\times$ over those in Minimum Mass Solar Nebula (MMSN) in the outer solar nebula (a $>$ 20 AU), increasing the oligarchic core masses and decreasing formation timescales for protoplanetary cores. A 10 $M_{\oplus }$ core can form on $\sim 10^6-10^7$ year timescales at 15 - 25 AU compared to $\sim 10^8$ years in the standard model,alleviating the major problem plaguing the core accretion model for gas/ice giant planet formation.

8 pages, 3 figures, 12pt preprint, emulateapj style; two sections added addressing shear-dominated accretion & disk conditions necessary for GI; Accepted for publication in the Astrophysical Journal

References in corpus (8)

• Towards a Deterministic Model of Planetary Formation I: a Desert in the Mass and Semi Major Axis Distributions of Extra Solar Planets
• Planetesimal Formation by Gravitational Instability
• Planet Formation by Coagulation: A Focus on Uranus and Neptune
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• Fast accretion of small planetesimals by protoplanetary cores
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• Particle Pile-ups and Planetesimal Formation

Cited by in corpus (5)

• The Last Gasp of Gas Giant Planet Formation: A Spitzer Study of the 5 Myr-old Cluster NGC 2362
• Spitzer/IRAC and JHKs Observations of h & chi Persei: Constraints on Protoplanetary Disk and Massive Cluster Evolution at ~ 10^{7} yr
• The Evolution of Protoplanetary Disks Around Millisecond Pulsars: The PSR 1257 +12 System
• Molecular Line Emission from Gravitationally Unstable Protoplanetary Disks
• Astrophysics in 2005