086434

We propose X-ray observations of nearby F-G-K young openPar20-40 MyrclosePar stars hosting transiting exoplanets comma recently discovered by TESS and Kepler openParK2closePar comma and included in follow-up campaigns with HARPSarrobaESO 3.6m and HARPS-NarrobaTNG. DS Tuc and HD 33512 host super-Earth-Neptune mass planets with inflated atmospheres comma due to strong irradiation from their host stars. V1298 Tau harbors a warm Jupiter still in contraction toward its final size. Our immediate objective is to assess X-ray spectral and time variability of the host stars comma so to characterize their activity level and the dose of high-energy radiation received by very young planets. Final goals are the determination of evolutionary paths of exoplanets in the mass-radius diagram comma and constraints for modeling planetary atmospheres.