WASP-43b tidal evolution

We observed the system with HARPS, whose data we present for the first time, and we also analyse the newly acquired JWST full-phase light curve. We fit jointly archival and new radial velocity and transit and occultation mid-times, including tidal decay, periastron precession and long-term acceleration in the system. We detected a tidal decay rate of dPa/dt=(-1.99+/-0.50)ms/yr and a periastron precession rate of d{omega}/dt=(0.1727^+0.0083^_-0.0089_)deg/d= (621.72^+29.88^_-32.04_)arcsec/d.

This is the first time that both periastron precession and tidal decay are simultaneously detected in an exoplanetary system. The observed tidal interactions can neither be explained by the tidal contribution to apsidal motion of a non-aligned stellar or planetary rotation axis nor by assuming non-synchronous rotation for the planet, and a value for the planetary Love number cannot be derived. Moreover, we exclude the presence of a second body - e.g. a distant companion star or a yet undiscovered planet -, down to a planetary mass of 0.3M_J_ and up to an orbital period of 3700 days.

We leave the question of the cause of the observed apsidal motion open.