We show how to estimate the size of spatially unresolved solar and stellar coronal flaring regions from the X-ray light curve and time-resolved temperature and emission measure values during the flare decay. Bymeans of extensive hydrodynamic modeling of decaying flaring loops, we propose and test a relationship between the decay time of the light curve in the band of a specific instrument and t...

The formation and evolution of active regions are inherently complex phenomena. Magnetic fields generated at the base of the convection zone follow a chaotic evolution before reaching the solar surface. In this article, we use a two-dimensional probabilistic cellular automaton to model the statistical properties of the magnetic patterns formed on the solar surface and to estimate the magnetic e...

We compile the most recently measured and calculated cross sections for processes relevant to annihilation of positrons in solar flares and present the final evaluated cross sections. We calculate the 511 keV annihilation line spectrum and relative strength of the 3γ continuum for each of the annihilation processes, using a Monte Carlo code that simulates the thermalization of and positronium p...