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

ROMINA PETRUCCI; EMILIANO JOFRÉ; YILEN GÓMEZ MAQUEO CHEW; TOBIAS HINSE; MARTIN MASEK; THIAM-GUAN TAN; MERCEDES GÓMEZ

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2020

0035-8711

We present a 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, Ṗ = −2.294 ms yr −1 , and a lower limit for the modified tidal qualityfactor 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⊕ 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 < 5600K dissipate tidal energy more efficiently than hotter stars. This tentative trendneeds to be confirmed with a larger sample of empirically measured Q*.