AD Leo from X-Rays to Radio: Are Flares Responsible for the Heating of Stellar Coronae?

In spring 1999, a long coordinated observing campaign was performed on the flare star AD Leo, including {\it EUVE}, {\it BeppoSAX}, the {\it VLA}, and optical telescopes. The campaign covered a total of 44 days. We obtained high-quality light curves displaying ongoing variability on various timescales, raising interesting questions on the role of flare-like events for coronal heating. We performed Kolmogorov-Smirnov tests to compare the observations with a large set of simulated light curves composed of statistical flares that are distributed in energy as a power law of the form ${\rm d}N/{\rm d}E \propto E^{-\alpha}$ with selectable index $\alpha$. We find best-fit $\alpha$ values slightly above a value of 2, indicating that the extension of the flare population toward small energies could be important for the generation of the overall X-ray emission.