1999ApJ...526L..49S

We present a theory to explain the observed universal correlation between flare temperature T and emission measure EM=n²V for solar and stellar flares (including solar microflares observed by Yohkoh as well as protostellar flares observed by ASCA), where n is the electron density and V is the volume. The theory is based on a magnetic reconnection model with heat conduction and chromospheric evaporation, assuming that the gas pressure of a flare loop is comparable to the magnetic pressure. This theory predicts the relation EM∝B^–5T^17/2, which explains well the observed correlation between EM and T in the range of 6x10⁶ K < T<10⁸ K and 10⁴⁴<EM<10⁵⁵ cm^–3 from solar microflares to protostellar flares, if the magnetic field strength B of a flare loop is nearly constant for solar and stellar flares.