The Thermal Starting Plume as an Acoustic Source

Abstract

We propose that solar acoustic oscillations are excited by localized cooling events and new downÑowplume formation at the solar surface. The excitation process involves, in successive stages, radiative cooling, buoyant acceleration, and advective inÑow. Pressure Ñuctuations induced at each stage result in monopolar, dipolar, and quadrupolar acoustic emission. We examine this excitation mechanism in detail, measure the acoustic energy output by such events, and discuss possible observational implications for helioseismic spectra.