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

Hot Jupiters orbiting rapidly rotating stars on inclined orbits undergo tidally induced nodal precession measurable over several years of observations. The Hot Jupiters WASP33 b and KELT9 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 WASP33 b and KELT9 b, respectively, in order to to model and improve upon their tidal precession parameters. Our work confirms the nodal precession for WASP33 b and presents the first clear detection of the precession of KELT9 b. We determine that WASP33 and KELT9 have gravitational quadrupole moments. We estimate the planets’ precession periods to be 1460 years and 890 years, respectively, and that they will cease to transit their host stars around the years 2090CE and 2074CE, respectively. Additionally, we investigate both planets’ tidal and orbital evolution, suggesting that a higheccentricity 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.

Modeling results for WASP-33 b data in 2016 (top panels from TULL; only one year shown), and 2019 (bottom panel; PEPSI). Left: Fourier-filtered residual map after subtracting the median line profile. The planet “Doppler shadow” is the diagonal blue track running from the bottom-right to the top-left. Occasional gaps are due to interpolation onto a time array with a fixed interval. Middle: Modeled Doppler Tomography signal. The overall gradient along the time axis is due to the shift of stellar radial velocity. The enhanced red background during transit is due to the fact that we set the line profile normalization to unity for all line profiles. Right: difference of the two maps on the left and middle panel.

Read more: Stephan et al. 2022, arXiv:2203.02546v1