A Discussion on the physics of the solar atmosphere - Optical and magnetic measurements of the photosphere and low chromosphere

Abstract

Sequences of photographs at a resolution of 1'" achieved during the past ten years have had a very significant impact upon our understanding of the development, mature structure and decay of active regions. Cinematic studies, especially, have allowed the emergence of new fields and their motions within the active centre to be studied in detail. Cinematic magnetic observations show how sunspots decay through the outward flight of tiny knots of magnetic flux. The newest advances are being made with arrays of photosensitive diodes at the focal planes of high dispersion spectrographs. The diode array at the Sacramento Peak Observatory produces simultaneous photometric observations at many different wavelengths throughout the visible and near infrared spectrum. Quantitative studies of magnetic fields and chromospheric structure are discussed. In particular, the moving magnetic features apparently produce surges in the superpenumbra around large sunspots.