Main Sequence Reinflation of Hot Jupiters

The cause of the unexpectedly large radii of hot Jupiters is a longstanding open question in exoplanetary science. The myriad of possible solutions that have been proposed each make subtly different predictions for the fine behavior of the mass-radius relationship over time, but investigations have been stymied by highly-uncertain estimates of the system age. In this work, we combine discovery paper, GAIA DR2, and 2MASS data to infer more precise stellar ages for the observed population of hot Jupiter hosts. Using this, we investigate whether planets grow in size (reinflate) as their parent stars evolve and brighten on the main sequence. Our analysis shows that planets do indeed reinflate over time, and we discuss the implications for the mechanism behind their inflation.