Discarding orbital decay in WASP-19b after one decade of transit observations. Issue 1 (31st October 2019)

• Record Type: Journal Article
• Authors: Petrucci, R; Jofré, E; Gómez Maqueo Chew, Y; Hinse, T C; Mašek, M; Tan, T-G; Gómez, M
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 491:Issue 1(2020)
• Page Start: 1243
• Page End: 1259
• Publication Date: 2019-10-31
• Subjects: techniques: photometric -- planets and satellites: individual: WASP-19b -- stars: individual: WASP-19 -- planetary systems; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stz3034
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: 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-yr 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, $\dot{P}=-2.294$ ms yr −1, and a lower limit for the modified tidal quality factor $Q^{\prime }_{\star } = (1.23 \pm 0.231) \times 10^{6}$ . Both are in agreement with previous works. This is the first estimation of $Q^{\prime }_{\star }$ directly derived from the mid-times of WASP-19b obtained through homogeneously analysed 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 $Q^{\prime }_{\star }$ values of 15 exoplanet host stars, which suggest that stars with T eff ≲ 5600 K dissipate tidal energy more efficiently than hotter stars. This tentative trend needs to be confirmed with a larger sample of empirically measured $Q^{\prime }_{\star }$ .