2616622

Target RA (J2000): 73.705780 and deg Target Dec (J2000): 22.14649 and deg Gaia GMag: 7.996 Programme ID: CH_PR140077 Programme Manager: KALMAN PI of observing programme: Benz Title of programme: Axis 3 - Photometric confirmation of planet candidate HD 31221b Abstract: HD 31221 is one of only a handful of Delta Scuti type stars hosting close-in sub-stellar companions. Such systems are excellent testbeds for understanding how planetary mass objects can influence the stellar oscillations while also being well-suited for atmospheric investigations. Based on the TESS light curve HD 31221b has a radius of 1.3 Jupiter radii and a mass that is compatible with either a giant planet or a brown dwarf. Its phase curve is dominated by the reflection effect owing to the high geometric albedo. The host star HD 31221 is a rapid rotator (v sin i = 175 km/s) which means that radial velocity measurements are not feasible. Because of the rapid rotation however the spin-orbit misalignment can also be derived. Combining the CHEOPS data with the existing TESS observations we will be able to narrow down the possible mass ranges of HD 31221 b while the two different bandpasses will let us carry out a detailed atmospheric investigation as well. [truncated! Please see actual data for full text]