Homogeneous studies of transiting extrasolar planets. III. Additional planets and stellar models

TL;DR

This study provides a homogeneous analysis of 30 transiting exoplanet systems, emphasizing the importance of accounting for stellar contamination and model dependence to accurately determine planetary and stellar properties.

Contribution

It introduces a consistent methodology for analyzing transiting exoplanets, including contamination correction and systematic error assessment using multiple stellar models.

Findings

Contamination of 5% can bias planetary radius measurements by 2%.

Systematic errors from stellar models are at least 1% for stellar mass.

Weak correlations found between planetary surface gravity, mass, and orbital period.

Abstract

I derive the physical properties of 30 transiting extrasolar planetary systems using a homogeneous analysis of published data. The light curves are modelled with the JKTEBOP code, with attention paid to limb darkening and eccentricity. The light from some systems is contaminated by faint nearby stars, which if ignored will systematically bias the results. I show that this must be accounted for using external measurements of the amount of contaminating light. A contamination of 5% is enough to make the measurement of a planetary radius 2% too low. The physical properties of the 30 transiting systems are obtained by interpolating in stellar model predictions to find the best match to their measured quantities. The error budgets are used to compile a list of systems which would benefit from additional observations. The systematic errors arising from the inclusion of stellar models are assessed by using five different theoretical models. This model dependence sets a lower limit on the accuracy of measurements of the system properties, and at worst is 1% for the stellar mass. The correlations of planetary surface gravity and mass with orbital period have significance levels of only 3.1 sigma and 2.3 sigma. The division of planets into two classes based on Safronov number is increasingly blurred. Most of the objects studied here would benefit from more photometry and/or spectroscopy, as well as a better understanding of low-mass stars.