| Popis: |
The 2.223 MeV line time profile for the flare of 16 December 1988 (for its third most intensive peak) is studied. The enhancement of plasma density in the deep photospheric layers below the flare region has been deduced. The energy spectrum of energetic solar particles (protons) is assumed to be formed by stochastic mechanism of acceleration. To compare our model calculations with observations, we use two possible functions for spectrum presentation, the power‐law and Bessel functions with spectral indices s and aT, respectively. The spectrum was shown to evolve with time, namely, the spectral index aT was found to increase from 0.005 to 0.1 during the decay phase of the burst, i.e., the proton spectrum has become harder. The density enhancement found in the flare of 16 December 1988 is consistent with our previous results for two other gamma‐ray flares, 6 November 1997 and 22 March 1991. This conclusion seems do not depend on the function of spectrum presentation and on the model of secondary neutron production by accelerated solar particles in the solar atmosphere. It is suggested that density enhancement in the deep layers of the solar photosphere may be rather common feature of powerful solar flares. |
