HIP 41378 velocity curve

According to stability considerations and a partial detection of the Rossiter-McLaughlin effect, the literature assessed Pd=278.36d as the most likely orbital period. We targeted HIP 41378d with CHEOPS at the predicted transit timing based on Pd=278.36d, but the observations show no transit.

We find that large transit timing variations (TTV), larger than 22.4-hours (duration related to the CHEOPS observation window) could explain this non-detection. We also investigate the possibility of an incorrect orbital solution, which would have major implications for our knowledge of this system. If Pd!=278.36d, we find that the periods minimizing the eccentricity are 101.22d and 371.14d.