摘要：Many of the known hot Jupiters are formally unstable to tidal orbital decay.The only hot Jupiter for which orbital decay has been directly detected is WASP-12, for which transit-timing measurements spanning more than a decade have revealed that the orbital period is decreasing at a rate of ${dP}/{dt}\approx {10}^{-9}$, corresponding to a reduced tidal quality factor of about 2 × 105.Here, we present a compilation of transit-timing data for WASP-12 and 11 other systems that are especially favorable for detecting orbital decay: KELT-16; WASP-18, 19, 43, 72, 103, 114, and 122; HAT-P-23; HATS-18; and OGLE-TR-56.For most of these systems we present new data that extend the time baseline over which observations have been performed.None of the systems besides WASP-12 display convincing evidence for period changes, with typical upper limits on dP/dt on the order of 10−9 or 10−10, and lower limits on the reduced tidal quality factor on the order of 105.One possible exception is WASP-19, which shows a statistically significant trend, although it may be a spurious effect of starspot activity.Further observations are encouraged.
