A Spectroscopic Method Based on the Shapes of Nuclear Deexcitation γ-Ray Lines in Solar Flares

摘要

The deexcitation γ -ray lines in solar flares result from energetic ions (e.g., protons, α -particles) interacting with the ambient nuclei in the solar atmosphere. The centroid and width of lines contain a wealth of information on the directionality, composition, and spectra of energetic ions as well as properties of the interaction sites. New calculations for the deexcitation γ -ray line shape analysis were done to study the properties of these ions. We calculate the shapes of the most intense deexcitation γ -ray lines in the solar flares, including the ~(12)C 4.439 MeV, ~(16)O 6.129 MeV, ~(24)Mg 1.369 MeV, and ~(28)Si 1.779 MeV lines, and explore the profiles of these line shapes as a function of the accelerated ion's energy spectra and composition, as well as the heliocentric angle of flare location. The merits of deexcitation γ -ray line shape analysis include (1) only a relatively small number of parameters being required in the fitting process and (2) the characteristics of accelerated ions with joint multi-line shape analysis being well constrained. We conclude that the measurement of the width and centroid of lines is an effective method for determining the properties of flare-accelerated ions.