Suppression of type I migration by disk winds
Abstract
Context. Planets less massive than Saturn tend to rapidly migrate inward in protoplanetary disks. This is the so-called type I migration. Simulations attempting to reproduce the observed properties of exoplanets show that type I migration needs to be significantly reduced over a wide region of the disk for a long time. However, the mechanism capable of suppressing type I migration over a wide region has remained elusive. The recently found turbulence-driven disk winds offer new possibilities.
Aims: We investigate the effects of disk winds on the disk profile and type I migration for a range of parameters that describe the strength of disk winds. We also examine the in situ formation of close-in super-Earths in disks that evolve through disk winds.
Methods: The disk profile, which is regulated by viscous diffusion and disk winds, was derived by solving the diffusion equation. We carried out a number of simulations and plot here migration maps that indicate the type I migration rate. We also performed N-body simulations of the formation of close-in super-Earths from a population of planetesimals and planetary embryos.
Results: We define a key parameter, Kw, which determines the ratio of strengths between the viscous diffusion and disk winds. For a wide range of Kw, the type I migration rate is presented in migration maps. These maps show that type I migration is suppressed over the whole close-in region when the effects of disk winds are relatively strong (Kw ≲ 100). From the results of N-body simulations, we see that type I migration is significantly slowed down assuming Kw = 40. We also show that the results of N-body simulations match statistical orbital distributions of close-in super-Earths.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- December 2015
- DOI:
- 10.1051/0004-6361/201527117
- arXiv:
- arXiv:1510.06010
- Bibcode:
- 2015A&A...584L...1O
- Keywords:
-
- planets and satellites: formation;
- planet-disk interactions;
- methods: numerical;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- 5 pages, 4 figures, accepted for publication in A&