Improved parameters for extrasolar transiting planets

Abstract

We present refined values for the physical parameters of transiting exoplanets, based on a self-consistent and uniform analysis of transit light curves and the observable properties of the host stars. Previously it has been difficult to interpret the ensemble properties of transiting exoplanets, because of the widely different methodologies that have been applied in individual cases. Furthermore, previous studies often ignored an important constraint on the mean stellar density that can be derived directly from the light curve. The main contributions of this work are 1) a critical compilation and error assessment of all reported values for the effective temperature and metallicity of the host stars; 2) the application of a consistent methodology and treatment of errors in modeling the transit light curves; and 3) more accurate estimates of the stellar mass and radius based on stellar evolution models, incorporating the photometric constraint on the stellar density. We use our results to revisit some previously proposed patterns and correlations within the ensemble. We confirm the mass-period correlation, and we find evidence for a new pattern within the scatter about this correlation: planets around metal-poor stars are more massive than those around metal-rich stars at a given orbital period. Likewise, we confirm the proposed dichotomy of planets according to their Safronov number, and we find evidence that the systems with small Safronov numbers are more metal-rich on average. Finally, we confirm the trend that led to the suggestion that higher-metallicity stars harbor planets with a greater heavy-element content.