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

¹ Observatoire de Genève, Département d’Astronomie, Université de Genève, Chemin des Maillettes 51, 1290 Versoix, Switzerland
e-mail: Jose.Almenara@unige.ch
² Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
³ Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, 13388 Marseille, France
⁴ Instituto de Astronomía y Física del Espacio (CONICET-UBA), C.C. 67, Sucursal 28, C1428EHA, Buenos Aires, Argentina

Received: 21 September 2016
Accepted: 11 October 2016

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.