2021MNRAS.502.2893K

Planet-planet scattering events can leave an observable trace of a planet's migration history in the form of orbital misalignment with respect to the stellar spin axis, which is measurable from spectroscopic time-series taken during transit. We present high-resolution spectroscopic transits observed with ESPRESSO of the close-in super-Earth π Men c. The system also contains an outer giant planet on a wide, eccentric orbit, recently found to be inclined with respect to the inner planetary orbit. These characteristics are reminiscent of past dynamical interactions. We successfully retrieve the planet-occulted light during transit, and find evidence that the orbit of π Men c is moderately misaligned with the stellar spin axis with λ = - 24_.^○0 ± 4_.^○1 (ψ= 26_.^○ 9⁺⁵.^○8 -4_.^○7 ^). This is consistent with the super-Earth π Men c having followed a high-eccentricity migration followed by tidal circularization, and hints that super-Earths can form at large distances from their star. We also detect clear signatures of solar-like oscillations within our ESPRESSO radial velocity time series, where we reach a radial velocity precision of ∼20 cm s^–1. We model the oscillations using Gaussian processes (GPs) and retrieve a frequency of maximum oscillation, ν_max = 2771⁺⁶⁵_–60 µHz. These oscillations make it challenging to detect the Rossiter-McLaughlin effect using traditional methods. We are, however, successful using the reloaded Rossiter-McLaughlin approach. Finally, in the appendix, we also present physical parameters and ephemerides for π Men c from a GP transit analysis of the full Transiting Exoplanet Survey Satellite Cycle 1 data.