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

Abstract

We present an intense, highly polarised, burst recorded on 13 February 1993 from the dMe flare star AD Leonis with the Arecibo1 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 positive drifts. Similar spikes are observed from the solar corona 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 stellar burst characteristics. We present estimates of the source's properties using realistic models of AD Leo's atmosphere.