Detecting the Wind-Driven Shapes of Extrasolar Giant Planets from Transit Photometry

Abstract

Several processes can cause the shape of an extrasolar giant planet's shadow, as viewed in transit, to depart from circular. In addition to rotational effects, cloud formation, non-homogenous haze production and movement, and dynamical effects (winds) could also be important. When such a planet transits its host star as seen from Earth, the asphericity will introduce a deviation in the transit lightcurve relative to the transit of a perfectly spherical (or perfectly oblate) planet. We develop a theoretical framework to interpret planet shapes. We then generate predictions for transiting planet shapes based on a published theoretical dynamical model of HD189733b. Using these shape models we show that planet shapes are unlikely to introduce detectable lightcurve deviations (those >~1e-5 of the host star), but that the shapes may lead to astrophysical sources of systematic error when measuring planetary oblateness, transit time, and impact parameter.

ApJ, accepted -- scheduled for publication 2009 December 1

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Cited by in corpus (6)

• Three-Dimensional Atmospheric Circulation Models of HD 189733b and HD 209458b with Consistent Magnetic Drag and Ohmic Dissipation
• Analytic Planetary Transit Light Curves and Derivatives for Stars with Polynomial Limb Darkening
• Towards consistent mapping of distant worlds: secondary-eclipse scanning of the exoplanet HD189733b
• The Impact of Circumplantary Jets on Transit Spectra and Timing Offsets for Hot-Jupiters
• Transiting exoplanets from the CoRoT space mission XXVII. CoRoT-28b, a planet orbiting an evolved star, and CoRoT-29b, a planet showing an asymmetric transit
• On the Effects of Planetary Oblateness on Exoplanet Studies