ИСТИНА

We propose a method of the plasma diagnostics in long-lived sources – post-eruptive arch systems, so-called “spiders”–, forming at the final stages of solar flares. As an example, we consider the 25.January 2007 event when the STEREO space craft registered radiation fluxes at 171, 195 284 and 304 A and the RATAN-600 registered the microwave flux. In order to determine the differential emission measure (DEM), we use an original probability method developed earlier by A. Urnov, where regularization does not required and solutions obtained do not depend on the temperature grid chosen. This allows us to estimate the DEM at the range from 30 000 K to 15 000 000 K. Microwave and the soft X-ray observational data for this event permit us to expand the temperature range and to construct the multi-temperature model of the arch system. We conclude that this thermal model is quite appropriate for explanation of post-eruptive phenomena of low and moderate power. We formulate conditions when such an approach could be reasonable for analysis quasi-stationary sources in outer atmospheres of the Sun and late-type stars. We discuss briefly physics of such phenomena without taking into account processes of particle acceleration.