A planet's rotation rate and axial tilt result from the transfer of angular momentum throughout its formation and dynamical evolution, thus acting as fossil signatures of its evolutionary history. While such measurements have been achieved for a few large outer companions (eg. Beta-Pic: Snellen 2014, AB Pic: PAlma-Bifani 2023), it remains a challenge for planets which can't be spatially separated from their stars. As close-in giants are generally expected to have formed further out, measuring their rotation parameters could provide valuable clues into possible migration histories.
A unique way to do this could be to exploit secondary eclipses. As portions of a planet's surface are occulted by its host star, the associated velocity components are removed from its spectrum, enabling to map rotation and wind velocities over the occulted surface. In a pilot program using SPIRou, we demonstrate the feasibility of detecting this eclipse signal on a Hot Jupiter for the first time, stacking multiple eclipses to reach a rotation constraint. Based on these promising results, we show how the ELT will expand the range of feasible targets to a wide set of close-in giants.
| Subject : | : | Oral presentation |
| Topics | : | Atmospheric characterization |
| Topics | : | Future prospects and techniques |
| PDF version | : |  PDF version |
