Presenter: Guo CHEN
Abstract:
Alkali lines, in particular the sodium D-lines, are critical atmospheric tracers for irradiated exoplanets. Pressure broadening of their line wings is a unique characteristic of clear skies, while the fine profile of their line cores can be linked to heating and cooling processes in the upper atmosphere. In this talk, I will present a comparative study of three irradiated low-density exoplanets with similar equilibrium temperatures but different masses. Using OSIRIS at 10.4 m GTC, we detected alkali metals in the low-resolution transmission spectra for all of them. We were able to resolve the pressure-broadened line wing in two, but only find a narrow line core in the third. We further acquired high-resolution transmission spectra using ESPRESSO at 8.2 m VLT and HARPS-N at 3.6 m TNG, which allows us to spectrally resolve the Na doublet in all three planets. I will present the retrieved atmospheric properties and discuss the prospects of combining different techniques to understand irradiated atmosphere as a whole.