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The Evolution of Protoplanetary Disks and the Diversity of Giant Planets. Extreme Solar Systems II September 2011 Ben Bromley Physics & Astronomy, University of Utah Scott Kenyon Smithsonian Astrophysical Observatory. Diversity of planets. the Solar System:
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The Evolution of Protoplanetary Disks and the Diversity of Giant Planets Extreme Solar Systems II September 2011 Ben Bromley Physics & Astronomy, University of Utah Scott Kenyon Smithsonian Astrophysical Observatory
Diversity of planets the Solar System: Is it extreme?
Planet formationtheory and practice • Young stars: gas/dust disk • Coagulation and dynamics; collisional accretion (many, small few, large) • Debris disks are signpostsof planet formation • Massive cores accrete gas (entrained debris helps, tGas ~ Myr)
Planet formation: difficulties • Dust-to-planetesimals How do planetesimals grow from micron-sized dust? • Migration How do planetary cores survive (fast, <Myr) migration? • Gas giant formation How do gas giants grow as gas disks vanish? Evolution of the gas disk is critical!
Modeling disk evolution • Initial conditions (Mdisk = 0.003—0.1 MStar; solid:gas ~ 0.01; S~ 1/a0.6—1.5) • Input physics (alpha disk: a = 10-5—0.01; tDisk ~ 1/a~ 1—10 Myr) • evolving the disk (solve diffusion equation) HSolid ~ √α Timing is everything.
Simulating planet formation PLANETESIMALS: pebbles—plutos FORMATION TIME: 0.1—1 Myr (cores) 1—10 Myr (J,N,SE) 10—100 Myr (Earths) a-viscosity… Coagulation code mergers, fragmentation photoionization growing planetesimals collisional cascade N-BODY CODEscattering, collisions gas accretion atmospheres (L,R) migration evolve gas, planetesimals, planets in concert
Growth of a planetary system 150 15 15 300 1000 10 m / MEarth semimajor axis (AU) log time (yr)
Growth of planetary systems: Jupiters++ (> 1 MJupiter) cumulative fraction log semimajor axis (AU)
Growth of planetary systems: Saturns (15 MEarth— 1 MJupiter ) cumulative fraction log semimajor axis (AU)
Growth of planetary systems: Earths++ (1—15 MEarth) cumulative fraction log semimajor axis (AU)
Growth of planetary systems: planetary masses cumulative fraction log mass (MJupiter)
Growth of planetary systems: Earths+ (1—15 MEarth) Diversity of planets: disk properties Jupiters (0—3) (2—4) (1—4) Saturns Super-Earths initial disk mass (M) (0—3) cumulative fraction (5—10) Earths (no gas giants) log disk viscosity parameter (α)
Results • Diverse systems of gas giants in alpha-disk model • Predictions: Multiplanet systems, ~MEarth—10’s of Mjupiter High mass, low viscosity disks: Jupiters Low mass, high viscosity disks: Neptunes, super-Earths • Next step: Include photoionization, migration….
Simulation summary photoionization
Simulation summary migration photoionization
Diversity of planets Dynamics (Architecture) Planetary structure (Radius – Mass, …) Goal: consistent evolution of full system