Magnetic activity in the eclipsing binary system KOI 1780

ABSTRACT We present the first comprehensive photometric analysis of magnetic activities of an eclipsing binary KOI 1780 using high-precision data from the Kepler mission. The system’s light curve is modelled to derive its fundamental parameters, and significant out-of-eclipse modulations are identified, attributable to strong flare activity from the primary component. Despite the detection of only 68 flares over a baseline of 1459. 48 d, the flare energies are notably high. Modelling with the One Phase Exponential Association function yields a Plateau value of 2. 160 0. 087 s, indicating flare energies comparable to those of UV Ceti-type stars. The cumulative flare frequency distribution aligns well with those of similar active systems. However, the derived Halftime of 13356. 5 s is considerably longer than typical for UV Ceti-type stars, implying enhanced magnetic activity likely driven by close binary interaction. Additionally, light curve asymmetries reveal the presence of three persistent cool starspots exhibiting differential longitudinal migration, with estimated periods of 3. 21 0. 02, 4. 93 0. 04, and 5. 25 0. 04 yr, respectively.