Short- and long- term X-ray variability of active fast rotator AB Dor

We present a comprehensive X-ray variability analysis of the ultrafast rotating active star AB Dor, using long-term observations. Our study reveals that flaring events, with energies up to 10^36 erg, are common and significantly impact the total X-ray emission. We observed variations in flare parameters like temperature and abundance, consistent with an inverse-FIP effect. Rotational modulation in flare-free light curves indicates persistent coronal active regions. Using our own developed light-curve inversion code, we imaged two distinct active regions separated by ∼180∘longitude. Furthermore, long-term data (1979-2022) show multiple periodicities, including a prominent ∼19.2 yr solar-like cycle and shorter ∼3.6 and ∼5.4 yr flip-flop like cycles.