Detection of the Neupert Effect in the Corona of an RS CVn Binary System   by XMM-Newton and the VLA
  The RS CVn-type binary $\sigma$ Geminorum was observed during a large, long-duration flare simultaneously with {\it XMM-Newton} and the VLA. The light curves show a characteristic time dependence that is compatible with the Neupert effect observed in solar flares: The time derivative of the X-ray light curve resembles the radio light curve. This observation can be interpreted in terms of a standard flare scenario in which accelerated coronal electrons reach the chromosphere where they heat the cool plasma and induce chromospheric evaporation. Such a scenario can only hold if the amount of energy in the fast electrons is sufficient to explain the X-ray radiative losses. We present a plausibility analysis that supports the chromospheric evaporation model. 
M. Guedel (1), M. Audard (1), K.W. Smith (1,2), E. Behar (3), A.J.   Beasley (4), R. Mewe (5) ((1) Paul Scherrer Institut, (...