Flare morphology with CHEOPS and TESS

Complex flares represent a significant percentage (>~30%) of the detected outburst events. Our findings suggest that high-impulse flares are more frequent than suspected from lower-cadence data, so that the most impactful flux levels that hit close-in exoplanets might be more concentrated than expected. We found significant differences in the duration distributions of single and complex flare components, but not in their peak luminosity.

A statistical analysis of the flare parameter distributions provides marginal support for their description with a log-normal instead of a power-law function, leaving the door open to several flare formation scenarios. We tentatively confirmed previous results about QPPs in high-cadence photometry, report the possible detection of a pre-flare dip, and did not find hints of photometric variability due to an undetected flare background.

The high-cadence study of stellar hosts might be crucial to evaluate the impact of their flares on close-in exoplanets, as their impulsive phase emission might otherwise be incorrectly estimated. Future telescopes such as PLATO and Ariel, thanks to their high-cadence capability, will help on this aspect. As the details of flare profiles and of the shape of their parameter distributions are made more accessible by ever increasing instrument precision and time resolution, the models used to interpret them and their role in star-planet interactions might need to be updated constantly.