Bulk density measurement of warm and temperate small-size exoplanets

The properties of warm and temperate small-size exoplanets with low stellar irradiation and/or long orbital periods, are so far not well known. Although  NASA's Kepler mission demonstrated the high occurrence rate of this type of planets, only a small number of temperate super-Earths and mini-Neptunes (with radii less than 4 Rearth) with a robust mass and bulk density determination were characterized. NASA's TESS space mission has been continuously monitoring the entire sky since 2018 to reveal transiting planets. With the extension of the mission, an increasing number of temperate small-sized exoplanet candidates are now detected and deserve radial-velocity (RV) follow-up. The ESPRESSO spectrograph on the ESO-VLT is one of the very few instruments capable of measuring the mass of temperate terrestrial exoplanets. The NIRPS near-infrared spectrograph, recently in operation on the 3.6m ESO telescope, has demonstrated its ability to measure mass of telluric planets orbiting M dwarfs, where the habitable zone is much closer to the star. ESA's PLATO space mission, which will be launched end 2026, is dedicated to the search for telluric planets close to and/or within the habitable zone using transit photometry. The first PLATO field (LOPS2) was recently selected in the southern hemisphere with a large overlap with the continuous viewing zone of TESS space mission. State-of-the-art stabilized spectrographs, like ESPRESSO, HARPS and NIRPS, will be intensively engaged in radial velocity follow-up of PLATO small-size exoplanet candidates to measure their mass and bulk densities. I will present recent results of warm and temperate small-size exoplanets with bulk densities characterization, on-going TESS RV follow-up activities as well as preparation for PLATO follow-up.