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 timeseries taken during transit .
We present high-resolution spectroscopic transits observed with ESPRESSO of the close-in super-Earth \pi 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 \pi Men c is moderately misaligned with the stellar spin axis with \lambda = \ang [ angle - symbol - over - decimal ] { -24.0 } \pm \ang [ angle - symbol - over - % decimal ] { 4.1 } ( \psi = \ang [ angle - symbol - over - decimal ] { 26.9 } ^ { +5.8 ^ { \circ } } _ { -4.7 ^ { \circ } } ) .
This is consistent with the super-Earth \pi Men c having followed a high-eccentricity migration followed by tidal circularisation , 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 timeseries , where we reach a radial velocity precision of \SI ∼ 20 \centi \metre \per \second .
We model the oscillations using Gaussian processes and retrieve a frequency of maximum oscillation , \nu _ { \mathrm { max } } { } = 2771 ^ { +65 } _ { -60 } \si { \micro \hertz } .
These oscillations makes it challenging to detect the Rossiter-McLaughlin effect using traditional methods .
We are , however , successful using the reloaded Rossiter-McLaughlin approach .
Finally , in an appendix we also present updated physical parameters and ephemerides for \pi Men c from a Gaussian process transit analysis of the full TESS Cycle 1 data .