Discarding orbital decay in WASP-19b after one decade of transit observations

PETRUCCI, R.; JOFRÉ, E. ; GÓMEZ MAQUEO CHEW, Y.; HINSE, T.C. ; MASEK, M. ; TAN, T.G.; GOMEZ, M.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2020 vol. 491 p. 1243 - 1259

0035-8711

We present an empirical study of orbital decay for the exoplanet WASP-19b, based on mid-time measurements of 74 complete transits (12 newly obtained by our team and 62 from the literature), covering a 10-year baseline. A linear ephemeris best represents the mid-transit times as a function of epoch. Thus, we detect no evidence of the shortening of WASP-19b´s orbital period and establish an upper limit of its steady changing rate, dP/dt = -2.294 ms yr^-1, and a lower limit for the modified tidal quality factor Q´_* = (1.23 +- 0.231) 10^6. Both are in agreement with previous works. This is the first estimation of Q´_* directly derived from the mid-times of WASP-19b obtained through homogeneously analyzed transit measurements. Additionally, we do not detect periodic variations in the transit timings within the measured uncertainties in the mid-times of transit. We are therefore able to discard the existence of planetary companions in the system down to a few M_earth in the first order mean-motion resonances 1:2 and 2:1 with WASP-19b, in the most conservative case of circular orbits. Finally, we measure the empirical Q´_* values of 15 exoplanet host stars which suggest that stars with Teff < 5600 K dissipate tidal energy more efficiently than hotter stars. This tentative trend needs to be conrmed with a larger sample of empirically measured Q´_*.