Exploring the population of intermediate sized exoplanets through ground-based transit surveys and radial velocity measurements
Constraining the transition between ice- and gas giants, and why ice giants do not evolve to become gas giants, is crucial to our understanding of planet formation and migration. Studying transiting exoplanets, for which we can characterise both bulk and atmospheric compositions, allows us to link the interior structure with volatile content to further constrain planetary formation pathways.
Intermediate sized exoplanet candidates orbiting relatively bright stars are targeted by the ground-based transit surveys NGTS and WASP-south. The latter is now focusing on shallow transits of bright stars after the installation of new 85 mm lenses. We check for false positives and measure precise masses and radii for these candidates with the high resolution spectrographs CORALIE and HARPS as well as the imagers EulerCam, TRAPPIST-South and TRAPPIST-North.
We will put our recently confirmed planets into the context of the transition between ice- and gas giants and explore the population of intermediate sized exoplanets as function of their host star properties, orbital period and insolation. E.g. constraining the location of the Neptune desert, which is constituted by a dearth of short period Neptunian planets.
In the near future, TESS will provide numerous exoplanet candidates transiting bright hosts stars. We will utilise upcoming near infra-red spectrographs, SPIROU at CFHT and NIRPS at ESO's 3.6m, to further characterise giant and sub-giants orbiting mainly M-dwarfs. Having precise masses of bloated Saturns and Neptunes will help guide future atmospheric characterisation in the era of JWST, which will improve our distinction of giant-planets.