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Target RA (J2000): 311.289703 and deg Target Dec (J2000): -31.34090 and deg Gaia GMag: 7.84 Programme ID: CH_PR140071 Programme Manager: SZABO PI of observing programme: Benz Title of programme: Axis 1 - Opening the treasure chest of the young golden system AU Mic with CHEOPS Abstract: AU Mic is a young (~22 Myr) active M1 star known to host two transiting warm Neptunes close to the 9:4 mean-motion resonance. Transit Timing Variations suggest that an additional resonant planet is likely present in the system. The rotation period of the star and the orbital period of AU Mic b are in a 7:4 spin-orbit commensurability. We also foundThere are systematic variations in the transit depth that correlate with the stars brightness strongly hampering the accuracy on the planetary radii. AU Mic displays differential rotation making it the youngest ``red star known to feature equator-to-pole spot migration. AU Mic is a ``young goldmine for planetary and stellar physics a treasure chest just waiting to be opened. Thanks to its short-cadence space-born photometry CHEOPS is uniquely well suited to seize this opportunity. We propose to carry out an intensive CHEOPS observing campaign of AU Mic. [truncated! Please see actual data for full text]