High resolution dynamic spectrum of a spectacular radio burst from the flare star AD Leonis

We present an intense, highly polarised, burst recorded on 13 February 1993 from the dMe flare star AD Leo- nis with the Arecibo 1 radio telescope at 1.4 GHz. The whole event lasts about 7 minutes, exhibits positive and negative drifts of the emission frequency with time, and narrow-band spikes reaching up to 350 mJy in 20 ms, some of which exhibit rapid positivedrifts.Similarspikesareobservedfromthesolarcorona and from the auroral zones of the magnetized planets, most of which are attributed to an electron-cyclotron maser instability. However, plasma waves are plausible to explain some of the stellarburstcharacteristics.Wepresentestimatesofthesource's properties using realistic models of AD Leo's atmosphere.