2040423

Target RA (J2000): 154.869095 and deg Target Dec (J2000): 6.58297 and deg Gaia GMag: 8.732 Programme ID: CH_PR230003 PI of observing programme: Heitzmann Title of programme: Two sub-Neptunes in short orbit around two bright young G and K stars Abstract: To understand the formation and evolution of planetary systems there is a crucial need to map exoplanets parameters as a function of time. Young planetary systems are the most important to focus on as they provide live snapshots of the processes at play and are currently dramatically under sampled. For planets discovered by survey mission such as the Transiting Exoplanet Survey Satellite (TESS) follow-ups required to characterise planetary orbits and atmospheres are only possible with a precise knowledge of the planets transit times. Thanks to CHEOPS we will be able to refine the transit time ephemerides of two sub Neptunes less than 500 Myr old and in short-orbit TOI-5082 b and TOI-5169 b. Five years from now and for both planets the transit mid-time uncertainty will shrink from ~2 hours when solely relying on TESS data to less than 10 minutes with CHEOPS observations. [truncated! Please see actual data for full text]