Jason W. Barnes et al. 2009 ApJ 706 877 doi:10.1088/0004-637X/706/1/877
Jason W. Barnes1, Curtis S. Cooper2,3, Adam P. Showman2 and William B. Hubbard2
Show affiliationsSeveral 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 the Earth, the asphericity will introduce a deviation in the transit light curve relative to the transit of a perfectly spherical (or perfectly oblate) planet. We develop a theoretical framework to interpret planetary 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 light-curve deviations (those >1 × 10–5 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.
eclipses; planets and satellites: individual (HD189733b, HD209458b); techniques: photometric
Issue 1 (2009 November 20)
Received 2009 May 6, accepted for publication 2009 October 13
Published 2009 November 6
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