The impact of circumplantary jets on transit spectra and timing offsets for hot Jupiters

Ian Dobbs-Dixon, Eric Agol, Adam Burrows

Research output: Contribution to journalArticlepeer-review


We present theoretical wavelength-dependent transit light curves for the giant planet HD209458b based on a number of state-of-the-art three-dimensional radiative hydrodynamical models. By varying the kinematic viscosity in the model, we calculate observable signatures associated with the emergence of a super-rotating circumplanetary jet that strengthens with decreased viscosity. We obtain excellent agreement between our mid-transit transit spectra and existing data from Hubble and Spitzer, finding the best fit for intermediate values of viscosity. We further exploit dynamically driven differences between eastern and western hemispheres to extract the spectral signal imparted by a circumplanetary jet. We predict that (1) the transit depth should decrease as the jet becomes stronger; (2) the measured transit times should show timing offsets of up to 6 s at wavelengths with higher opacity, which increases with jet strength; (3) wavelength-dependent differences between ingress and egress spectra increase with jet strength; and (4) the color-dependent transit shape should exhibit stronger asymmetry for planets with stronger jets. These techniques and trends should be valid for other hot Jupiters as well. Observations of transit timing offsets may be accessible with current instrumentation, though the other predictions may require the capabilities of the James Webb Space Telescope and other future missions. Hydrodynamical models utilized solve the three-dimensional Navier-Stokes equations together with decoupled thermal and radiative energy equations and wavelength-dependent stellar heating.

Original languageEnglish (US)
Article number87
JournalAstrophysical Journal
Issue number2
StatePublished - Jun 1 2012


  • hydrodynamics
  • infrared: planetary systems
  • planets and satellites: atmospheres
  • radiative transfer
  • techniques: spectroscopic

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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