2310923

Target RA (J2000): 93.959236 and deg Target Dec (J2000): 16.02391 and deg Gaia GMag: 11.78 Programme ID: CH_PR240002 PI of observing programme: Vach Title of programme: CHEOPS transits of two 48-Myr mini-Neptunes in the Taurus-Orion II moving group Abstract: Within the first 100 Myr planets undergo critical evolutionary events. Observing young planetary systems allow us to gain insights into the physical processes that shape the mature planetary population. TIC 434398831 is a pre-main-seqeunce Sun-like star (G7V G = 11.7893) hosting two transiting mini-Neptunes. Gaia kinematics place TIC 434398831 in the 48-Myr Taurus-Orion II moving group. We identified two planetary candidates TIC 434398831.01 (Rp = 3.65 Rearth P = 3.61 days) and TIC 434398831.02 (Rp = 5.41 Rearth P = 6.12 days) through an independent search for young planets located in known moving groups from the TESS's Full Frame Images (FFIs) light curves. We propose to use 4 visits of CHEOPS to observe two transits of both TIC 434398831.01 and TIC 434398831.02 which is necessary for the confirmation of this exemplar system as high-precision space-based photometry is needed to overcome the photometric modulations of the young star. Our CHEOPS observations will have the capability to anchor the optical transit depths of the two young planets which will enable us to distinguish between different cloud and haze scenarios in future atmospheric observations. [truncated! Please see actual data for full text]