Observing White-Light Flares
Abstract
Observational techniques and instrumentation for tracking the occurrence of solar white light flares back to their origin are discussed. The rare events have been found to happen in the chromospheric and coronal regions over sunspots, and are thought to be the release of accumulated energy breaking free from the magnetic field lines and reforming into simpler structures. Use of an achromatic f/15 objective lens, together with a reimaging system for field magnification as a prelude to 35 mm photography, at the Sacramento Peak Observatory is described. A Wollaston prism is also used to split the image into two beams for detection of intensity variations due to polarization, which has thus far not been observed in the white light flares. Spectroscopic data indicate visual emission due to negatively-charged hydrogen ions in the upper photosphere, and shorter wavelength neutral hydrogen Balmer continuum features. A white light flare can be up to 300% as brilliant as the surrounding region, and involve several percent of the total spontaneous solar output.
- Publication:
-
Sky and Telescope
- Pub Date:
- March 1983
- Bibcode:
- 1983S&T....65..226N
- Keywords:
-
- Astronomical Photography;
- Polarimeters;
- Solar Flares;
- Solar Instruments;
- Sunlight;
- Solar Atmosphere;
- Solar Radiation;
- Solar Spectra;
- Solar Physics