Orbital Migration of Protoplanets in a Marginally Gravitationally Unstable Disk

Abstract

Core accretion and disk instability require giant protoplanets to form in the presence of disk gas. Protoplanet migration models generally assume disk masses low enough that the disk's self-gravity can be neglected. However, disk instability requires a disk massive enough to be marginally gravitationally unstable (MGU). Even for core accretion, a FU Orionis outburst may require a brief MGU disk phase. We present a new set of three dimensional, gravitational radiation hydrodynamics models of MGU disks with multiple protoplanets, which interact gravitationally with the disk and with each other, including disk gas mass accretion. Initial protoplanet masses are 0.01 to 10 $M_{\oplus }$ for core accretion models, and 0.1 to 3 $M_{Jup}$ for Nice scenario models, starting on circular orbits with radii of 6, 8, 10, or 12 AU, inside a 0.091 $M_{\odot }$ disk extending from 4 to 20 AU around a $1M_{\odot }$ protostar. Evolutions are followed for up to $\sim$ 4000 yr and involve phases of relative stability ($e\sim$ 0.1) interspersed with chaotic phases ($e\sim$ 0.4) of orbital interchanges. The 0.01 to 10 $M_{\oplus }$ cores can orbit stably for $\sim$ 1000 yr: monotonic inward or outward orbital migration of the type seen in low mass disks does not occur. A system with giant planet masses similar to our Solar System (1.0, 0.33, 0.1, 0.1 $M_{Jup}$) was stable for over 1000 yr, and a Jupiter-Saturn-like system was stable for over 3800 yr, implying that our giant planets might well survive a MGU disk phase.

27 pages, 7 figures, 3 tables - in press, ApJ

References in corpus (6)

• Direct Imaging of Multiple Planets Orbiting the Star HR 8799
• Obliquities of Hot Jupiter host stars: Evidence for tidal interactions and primordial misalignments
• Origin of the Structure of the Kuiper Belt during a Dynamical Instability in the Orbits of Uranus and Neptune
• Type I planetary migration in a self-gravitating disk
• On the convergence of the critical cooling timescale for the fragmentation of self-gravitating discs
• Cosmochemical Consequences of Particle Trajectories During FU Orionis Outbursts by the Early Sun

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• Filling in the Gaps: Can Gravitationally Unstable Discs Form the Seeds of Gas Giant Planets?
• Orbital Migration of Protoplanets in a Marginally Gravitationally Unstable Disk. II. Migration, Merging, and Ejection
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