Inferring the heavy element content of hot Jupiters

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Inferring the heavy element content of hot Jupiters

Post by Sirius_Alpha on 2nd May 2011, 9:10 pm

The Heavy Element Masses of Extrasolar Giant Planets, Revealed

We investigate a population of transiting planets that receive relatively modest stellar insolation and for which the heating mechanism that inflates hot Jupiters does not appear to be significantly active. Using the observed transit radius as a constraint and assuming that the unknown heating mechanism is not a heating source, we use structure and thermal evolution models to infer the amount of heavy elements within each of these planets. There is a correlation between the stellar metallicity and the mass of heavy elements in its transiting planet(s). It appears that all giant planets posses a minimum of $\sim$ 10-15 Earth masses of heavy elements, with planets around metal-rich stars having larger heavy element masses. This relationship provides an important constraint on planet formation and planetesimal accretion, and suggests large amounts of heavy elements within planetary H/He envelopes. We suggest that the observed correlation can soon also be applied to inflated planets, such that the interior heavy element abundance of these planets could be determined. This would lead to much better constraints on the magnitude of the energy source that inflates the more highly-irradiated planets. We point to future directions for planetary population synthesis models and suggest future correlations. Saturn- and Jupiter-like enrichments above solar composition are a hallmark of all the gas giants in the sample, even planets of several Jupiter masses. This appears to be the first evidence that extrasolar giant planets, as a class, are enhanced in heavy elements.

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