Save the Planet, Feed the Star: How Super-Earths Survive Migration and Drive Disk Accretion

Journal Article · Thu Apr 20 04:00:00 EDT 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/AA6934· OSTI ID:22872784

Fung, Jeffrey; Chiang, Eugene ^[1]

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1. Department of Astronomy, University of California at Berkeley, Campbell Hall, Berkeley, CA 94720-3411 (United States)

Two longstanding problems in planet formation include (1) understanding how planets survive migration, and (2) articulating the process by which protoplanetary disks disperse—and in particular how they accrete onto their central stars. We can go a long way toward solving both problems if the disk gas surrounding planets has no intrinsic diffusivity (“viscosity”). In inviscid, laminar disks, a planet readily repels gas away from its orbit. On short timescales, zero viscosity gas accumulates inside a planet’s orbit to slow Type I migration by orders of magnitude. On longer timescales, multiple super-Earths (distributed between, say, ∼0.1–10 au) can torque inviscid gas out of interplanetary space, either inward to feed their stars, or outward to be blown away in a wind. We explore this picture with 2D hydrodynamics simulations of Earths and super-Earths embedded in inviscid disks, confirming their slow/stalled migration even under gas-rich conditions, and showing that disk transport rates range up to ∼10{sup −7} M{sub ⊙} yr{sup −1} and scale as M-dot ∝ΣM{sub p}{sup 3/2}, where Σ is the disk surface density and M {sub p} is the planet mass. Gas initially sandwiched between two planets is torqued past both into the inner and outer disks. In sum, sufficiently compact systems of super-Earths can clear their natal disk gas in a dispersal history that may be complicated and non-steady but which conceivably leads over Myr timescales to large gas depletions similar to those characterizing transition disks.

• OSTI ID: 22872784
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 839; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCRETION DISKS
COMPUTERIZED SIMULATION
DENSITY
HYDRODYNAMICS
INTERACTIONS
INTERPLANETARY SPACE
MASS
PLANETS
PROTOPLANETS
SATELLITES
STARS
STELLAR WINDS
SURFACES
VISCOSITY