Main sequence hot Jupiter hosts with good astrometry

However, orbital decay has never been unambiguously observed. We use data from Gaia Data Release 2 (Cat.

I/345) to show that hot Jupiter host stars have a smaller Galactic velocity dispersion than a similar population of stars without hot Jupiters. Since Galactic velocity dispersion is correlated with age, this observation implies that the population of hot Jupiter host stars is on average younger than the field population. The best explanation for this inference is that tidal interactions cause hot Jupiters to inspiral while their host stars are on the main sequence.