Detecting the general relativistic orbital precession of the exoplanet HD 80606b

Institut d’Astrophysique de Paris, UMR 7095, CNRS, Sorbonne Université, 98 bis boulevard Arago, 75014 Paris, France
e-mail: luc.blanchet@iap.fr, hebrard@iap.fr, francois.larrouturou@iap.fr

Received: 16 April 2019
Accepted: 28 May 2019

Abstract

We investigate the relativistic effects in the orbital motion of the exoplanet HD 80606b with a high eccentricity of e ≃ 0.93. We propose a method to detect these effects (notably the orbital precession) based on measuring the successive eclipse and transit times of the exoplanet. In the case of HD 80606b, we find that in ten years (after approximately 33 periods) the instants of transits and eclipses are delayed with respect to the Newtonian prediction by about three minutes due to relativistic effects. These effects can be detected by comparing at different epochs the time difference between a transit and the preceding eclipse, and should be measurable by comparing events already observed on HD 80606 in 2010 with the Spitzer satellite together with those to be observed in the future with the James Webb Space Telescope.