The optical depth of white-light flare continuum

Abstract

The white-light continuum emission of a solar flare remains a puzzle as regards its height of formation and its emission mechanism(s). This continuum, and its extension into the near UV, contain the bulk of the energy radiated by a flare, and so its explanation is a high priority. We describe a method to determine the optical depth of the emitting layer and apply it to the well-studied flare of 2002 July~15, making use of MDI pseudo-continuum intensity images. We find the optical depth of the visible continuum in all flare images, including an impulsive ribbon structure to be small, consistent with the observation of Balmer and Paschen edges in other events.

References in corpus (3)

• Impulsive phase flare energy transport by large-scale Alfven waves and the electron acceleration problem
• Local re-acceleration and a modified thick target model of solar flare electrons
• The effect of flares on total solar irradiance

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