Dynamic response of an isothermal static corona to finite-amplitude disturbances

Abstract

The velocity evolution of sprays, surges and fast ejections is characterized by a rapid acceleration followed by a slowdown. In contrast, eruptive prominences show a velocity evolution with a slow increase followed by a rapid acceleration. We examine the physical causes which differentiate these two characteristic velocity evolutions, and study the dynamic responses of the solar corona. For simplicity, the ascending disturbances are modelled as purely radial adiabatic flows caused by finite-amplitude perturbations (pulses) in an initially isothermal, static corona. It is shown that the resultant flow depends strongly on the nature of the disturbing causes. In particular, the coronal response to sprays and fast ejections can be identified with temperature and velocity pulses at the bottom of the corona, with surges related to shorter pulses, while the slow moving eruptive prominences are correlated with density pulses. It is shown that for large flare sprays 5 × 10³⁹ particles can be injected into the solar wind.