Free Oscillations of the Sun and Their Possible Stimulation by Solar Flares

A large solar flare can raise the temperature of the underlying photosphere by 10 percent. The resulting thermal expansion exerts upon the solar interior a mechanical impulse whose kinetic energy is 1025 ergs. This will stimulate free modes of oscillation of the entire Sun, and the initial amplitudes of the more easily observable modes are calculated. Preliminary estimates of the effects of radiation damping and turbulent viscosity indicate that damping times will typically he longer than 1 day for the modes of most interest.