Nodal Precession and Tidal Evolution of Two Hot-Jupiters: WASP-33 b and KELT-9 b

Abstract

Hot Jupiters orbiting rapidly rotating stars on inclined orbits undergo tidally induced nodal precession measurable over several years of observations. The Hot Jupiters WASP-33 b and KELT-9 b are particularly interesting targets as they are among the hottest planets found to date, orbiting relatively massive stars. Here, we analyze archival and new data that span 11 and 5 years for WASP-33 b and KELT-9 b, respectively, in order to to model and improve upon their tidal precession parameters. Our work confirms the nodal precession for WASP-33 b and presents the first clear detection of the precession of KELT-9 b. We determine that WASP-33 and KELT-9 have gravitational quadrupole moments $(6.3^{+1.2}_{-0.8})\times10^{-5}$ and $(3.26^{+0.93}_{-0.80})\times10^{-4}$, respectively. We estimate the planets' precession periods to be $1460^{+170}_{-130}$ years and $890^{+200}_{-140}$ years, respectively, and that they will cease to transit their host stars around the years $2090^{+17}_{-10}$~CE and $2074^{+12}_{-10}$~CE, respectively. Additionally, we investigate both planets' tidal and orbital evolution, suggesting that a high-eccentricity tidal migration scenario is possible to produce both system architectures and that they will most likely not be engulfed by their hosts before the end of their main sequence lifetimes.