Estimation of the flaring loop size from the thermal energy evolution during the rise phase Original Research Article

Hydrodynamic modelling of flaring loops points to the possibility of estimating the equivalent loop size from the rate of thermal energy increase during the flare rise phase. The low sensitivity of X-ray detectors limits the applicability of this method to solar flares and the most intense stellar events. This disadvantage can however be avoided by converting the time evolution of energy to that of X-ray flux. The method has been applied to the case of two stellar flares observed by the Medium Energy Instrument (ME) on board the EXOSAT satellite. Comparison of the results with flare evolution during the decay phase is discussed in terms of the heating function.