Time-dependent ionization equilibrium and line radiation under flarelike conditions

The results of calculations of time-dependent ionization equilibrium and line emission are presented and compared with the values obtained under the assumption that steady-state conditions prevail. In the models considered, it is assumed that the electron density is constant (= 10 cm-2) and that the temperature increases by a factor of 10 from 3 X 10 K on timescales ranging from 100 to 300 5 and decays back to 3 X 101 K on a timescale ranging from 600 to 1400 5. Ions of oxygen and silicon are considered, and it is found that the spectrum is softer during the rise and harder during the fall than predicted by the steady-state approximatinn.