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Precise Radius Estimates for the Exoplanets WASP-1b and WASP-2b

David Charbonneau·Joshua N. Winn·Mark E. Everett·David W. Latham·Matthew J. Holman·Gilbert A. Esquerdo·Francis T. O'Donovan
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Abstract

We present precise z-band photometric time series spanning times of transit of the two exoplanets recently discovered by the SuperWASP collaboration. We find planetary radii of 1.44 +/- 0.08 R_J and 1.04 +/- 0.06 R_J for WASP-1b and WASP-2b, respectively. These error estimates include both random errors in the photometry and also the uncertainty in the stellar masses. Our results are 5 times more precise than the values derived from the discovery data alone. Our measurement of the radius of WASP-2b agrees with previously published models of hot Jupiters that include both a 20-M_Earth core of solid material and the effects of stellar insolation. In contrast, we find that the models cannot account for the large size of WASP-1b, even if the planet has no core. Thus, we add WASP-1b to the growing list of hot Jupiters that are larger than expected. This suggests that ``inflated'' hot Jupiters are more common than previously thought, and that any purported explanations involving highly unusual circumstances are disfavored.

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David Charbonneau, Joshua N. Winn, Mark E. Everett, David W. Latham, Matthew J. Holman, Gilbert A. Esquerdo, Francis T. O'Donovan. 2006-10-19. Precise Radius Estimates for the Exoplanets WASP-1b and WASP-2b. https://doi.org/10.1086/512008

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