State of plasma in impulsive phase of solar flare

Abstract

Studying of characteristics of solar activity is one of the major astrophysical problems. Special interest is represented with solar flares. It is possible to receive the important information on physical processes causing this phenomenon on the basis of the analysis of radioastronomical observations in mm range of wavelengths. The area of flare is optically thin in mm range. Therefore observations on these waves allow looking inside of solar flare to estimate a condition flare environments, its temperature, density of plasma, magnitude of magnetic field, a ratio of gas and magnetic pressure. Apparent emission is caused by the gyro-synchrotron mechanism of radiation of a stream of the accelerated nonthermal electrons in magnetic tubes and has high sensitivity to fluctuations of a magnetic field. In magnetic tubes there are magnetohydrodynamic waves. Their resonance in tubes and formation of standing waves causes longitudinal modulation of a magnetic field and modulation of a radiation field. Its dynamic spectrum allows to determine frequencies of fluctuations of radiation, a depth of modulation of a magnetic field magnetohydrodynamic oscillations. Simultaneous observations of examined solar flare in an ultraviolet range allow to receive images of hot magnetic tubes. The spatial size of flexural oscillations of tubes and frequency of oscillations of radiation determine value of velocity of a resonating Alfven wave. Data of measurements and the characteristic of a dynamic spectrum allow to determine parameters of plasma in a impulsive phase of solar flare under the formulas received by us.