Atmospheric escape by magnetically driven wind from gaseous planets

Yuki A. Tanaka, Takeru K. Suzuki, Shu Ichiro Inutsuka

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)

Abstract

We calculate the mass loss driven by magnetohydrodynamic (MHD) waves from hot Jupiters by using MHD simulations in one-dimensional flux tubes. If a gaseous planet has a magnetic field, MHD waves are excited by turbulence at the surface, dissipate in the upper atmosphere, and drive gas outflows. Our calculation shows that mass-loss rates are comparable to the observed mass-loss rates of hot Jupiters; therefore, it is suggested that gas flow driven by MHD waves can play an important role in the mass loss from gaseous planets. The mass-loss rate varies dramatically with the radius and mass of a planet: a gaseous planet with a small mass but an inflated radius produces a very large mass-loss rate. We also derive an analytical expression for the dependence of mass-loss rate on planet radius and mass that is in good agreement with the numerical calculation. The mass-loss rate also depends on the amplitude of the velocity dispersion at the surface of a planet. Thus, we expect to infer the condition of the surface and the internal structure of a gaseous planet from future observations of mass-loss rate from various exoplanets.

Original languageEnglish
Article number18
JournalAstrophysical Journal
Volume792
Issue number1
DOIs
Publication statusPublished - 2014 Sep 1
Externally publishedYes

Keywords

  • magnetohydrodynamics (MHD)
  • planets and satellites: atmospheres
  • planets and satellites: gaseous planets
  • planets and satellites: magnetic fields

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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