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Title: Non-axisymmetric flows on hot Jupiters with oblique magnetic fields

Giant planets that reside in close proximity to their host stars are subject to extreme irradiation, which gives rise to thermal ionization of trace alkali metals in their atmospheres. On objects where the atmospheric electrical conductivity is substantial, the global circulation couples to the background magnetic field, inducing supplementary fields and altering the nature of the flow. To date, a number of authors have considered the influence of a spin-pole aligned dipole magnetic field on the dynamical state of a weakly ionized atmosphere and found that magnetic breaking may lead to significantly slower winds than predicted within a purely hydrodynamical framework. Here, we consider the effect of a tilted dipole magnetic field on the circulation and demonstrate that in addition to regulating wind velocities, an oblique field generates stationary non-axisymmetric structures that adhere to the geometry of the magnetic pole. Using a kinematic perturbative approach, we derive a closed-form solution for the perturbed circulation and show that the fractional distortion of zonal jets scales as the product of the field obliquity and the Elsässer number. The results obtained herein suggest that on planets with oblique magnetic fields, advective shifts of dayside hotspots may have substantial latitudinal components. This prediction maymore » be tested observationally using the eclipse mapping technique.« less
Authors:
 [1] ;  [2]
  1. Division of Geological and Planetary Sciences, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States)
  2. Department of Physics, University of Toronto, 60 St. George Street, Toronto, ON M5S 1A7 (Canada)
Publication Date:
OSTI Identifier:
22370515
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 794; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ALKALI METALS; AXIAL SYMMETRY; DIPOLES; ECLIPSE; ELECTRIC CONDUCTIVITY; FORECASTING; IRRADIATION; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; MATHEMATICAL SOLUTIONS; PLANETS; SATELLITE ATMOSPHERES; SATELLITES; STARS; WIND