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Well mixed PowerPoint Presentation

Well mixed

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Well mixed

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  1. CATP funded by Dead Zones & the Diversity of Exoplanetary Systems Yasuhiro Hasegawa & Ralph E Pudritz Dept. of Physics & Astronomy, McMaster University, Canada Dust distribution Dead Zone • 1. Introduction: the Diversity of Exoplanetary System • 2. The Problem: Dust Settling & Rapid Planetary Migration (NEW RESULTS!!) • a) Disk Structures b) Type I Migration c) Type II Migration • 3. Possible Solutions: Thermal Barriers Induced by Dead Zones • a) Disk Structures b) Temperature at the mid-plane c) Migration Time & Rate • 4. Next Step: Combination of Our Barriers with Density Barriers Gas + Dust distribution • the Mass-Period relation: all detected exoplanetary systems are consolidated • Many Hot Jupiters: gas giants with < 3day orbital periods (called Hot Jupiters)are piled up • the diversity: planetary masses & orbital periods days • (Udry & Santos 2007; http://exoplanet.eu) Well mixed Planetary Migration Potentially Explains Such Diversity Dust settling: ubiquitous for disks around any type of stars • Rapid planetary migration: • In standard disk models, the migration • timescale is times faster than • the disk life time ( years) • More rapid migration with dust settling: • Dust settling results in even more rapid • migration by up to a factor of about 2, • as a consequence of flatter disk structures • (Hasegawa & Pudritz, 2010c, submitted) • Two-layer disk structures: • Hasegawa & Pudritz, 2010a performed • Monte Carlo simulations, and showed • the hot surface and cool mid-plane • regions [1] • Flatter structures: • dust settling results in the hotter • surface &the cooler mid-plane • reducing the gap-opening mass • Dust settling decreases the gap- • opening mass by a factor of 2 • Even slower type II migration • Dust settling slows type II • migration by a factor of 2 • a dusty wall: (Hasegawa & Pudritz 2010a) • it is left at the boundary due to the • enhanced dust settling in the dead zone • a positive temperature gradient: • it is produced by the back heating of • the dead zone by such a hot wall • planets trapping: (Hasegawa & Pudritz 2010b) • such a temperature structure reverses the torque balance • Density Barriers: dead zones also provide density barriers at their outer boundary by piling up gas, as a result of • the viscous evolution (Matsumura, Pudritz, & Thommes 2009) • Expectations: these two barriers can play a significant role for planets with longer periods ( days ) References : [1] Chiang, E. I., & Goldreich, P. 1997, ApJ, 490, 368, Matsumura, S., Pudritz, R. E., & Thommes, E. W. 2009, ApJ, 691, 1764, Hasegawa, Y., & Pudritz, R. E. 2010a, MNRAS, 401, 143, Hasegawa, Y., & Pudritz, R. E. 2010b, ApJ, 710, L167, Hasegawa, Y., & Pudritz, R. E. 2010c, submitted