Context : The presence and strength of a stellar magnetic field and activity is rooted in a star’s fundamental parameters such as mass and age .
Can flares serve as an accurate stellar ” clock ” ?

Aims : To explore if we can quantify an activity-age relation in the form of a flaring-age relation , we measured trends in the flaring rates and energies for stars with different masses and ages .

Methods : We investigated the time-domain photometry provided by Kepler ’s follow-up mission K2 and searched for flares in three solar metallicity open clusters with well-known ages , M45 ( 0.125 Gyr ) , M44 ( 0.63 Gyr ) , and M67 ( 4.3 Gyr ) .
We updated and employed the automated flare finding and analysis pipeline Appaloosa , originally designed for Kepler .
We introduced a synthetic flare injection and recovery subroutine to ascribe detection and energy recovery rates for flares in a broad energy range for each light curve .

Results : We collected a sample of 1 761 stars , mostly late-K to mid-M dwarfs and found 751 flare candidates with energies ranging from 4 \cdot 10 ^ { 32 } erg to 6 \cdot 10 ^ { 34 } erg , of which 596 belong to M45 , 155 to M44 , and none to M67 .
We find that flaring activity depends both on T _ { \mathrm { eff } } , and age .
But all flare frequency distributions have similar slopes with \alpha \approx 2.0 - 2.4 , supporting a universal flare generation process .
We discuss implications for the physical conditions under which flares occur , and how the sample ’ s metallicity and multiplicity affect our results .

Conclusions :