  Hot Jupiters have proven themselves to be a rich class of exoplanets which
test our theories of planetary evolution and atmospheric dynamics under extreme
conditions. Here, we present three-dimensional magnetohydrodynamic simulations
and analytic results which demonstrate that a dynamo can be maintained in the
thin, stably-stratified atmosphere of a hot Jupiter, independent of the
presumed deep-seated dynamo. This dynamo is maintained by conductivity
variations arising from strong asymmetric heating from the planets' host star.
The presence of a dynamo significantly increases the surface magnetic field
strength and alters the overall planetary magnetic field geometry, possibly
affecting star-planet magnetic interactions.
