Absolute densities, masses, and radii of the WASP-47 system determined dynamically

TL;DR

This study models the WASP-47 system using combined light curve and radial velocity data to derive absolute planetary and stellar parameters without relying on stellar models, achieving competitive precision.

Contribution

It introduces a self-consistent dynamical modeling approach that derives absolute densities, masses, and radii directly from observational data in a multi-planet system.

Findings

Achieved approximately 22% precision for stellar and planetary radii.

Obtained 40-60% precision for planetary and stellar masses.

Densities determined with 1.5-38% precision, consistent with previous measurements.

Abstract

We present a self-consistent modelling of the available light curve and radial velocity data of WASP-47 that takes into account the gravitational interactions between all known bodies in the system. The joint analysis of light curve and radial velocity data in a multi-planetary system allows deriving absolute densities, radii, and masses without the use of theoretical stellar models. For WASP-47 the precision is limited by the reduced dynamical information that is due to the short time span of the K2 light curve. We achieve a precision of around 22% for the radii of the star and the transiting planets, between 40% and 60% for their masses, and between 1.5% and 38% for their densities. All values agree with previously reported measurements. When theoretical stellar models are included, the system parameters are determined with a precision that exceeds that achieved by previous studies, thanks to the self-consistent modelling of light curve and radial velocity data.