SIMBAD references

An intense radio flare on the dMe star AD Leo, observed with the Effelsberg radio telescope and spectrally resolved in a band of 480 MHz centred at 4.85GHz is analysed. A lower limit of the brightness temperature of the totally right handed polarized emission is estimated as T_b∼5x10¹⁰K (with values T_b>3x10¹³K considered to be more probable), which requires a coherent radio emission process. In the interpretation we favour fundamental plasma radiation by mildly relativistic electrons trapped in a hot and dense coronal loop above electron cyclotron maser emission. This leads to densities and magnetic field strengths in the radio source of n∼2x10¹¹cm^–3 and B∼800 G. Quasi-periodic pulsations during the decay phase of the event suggest a loop radius of r∼7x10⁸cm. A filamentary corona is implied in which the dense radio source is embedded in hot thin plasma with temperature T≥2x10⁷K and density n_ext≤10^–2n. Runaway acceleration by sub-Dreicer electric fields in a magnetic loop is found to supply a sufficient number of energetic electrons.