White-Light Flares Observed by YOHKOH
Abstract
The Yohkoh observatory is producing a first sample of white-light flares observed from space. We present observations of four of them, all X-class events. The Yohkoh (SXT) white-light data typically have a 12-s cadence for images with 2.''46 pixels over a field of view of 2.'62 in one of two broad-band optical filters, and the 1991 November 15 flare produced a brightness increase of about 38% over the photospheric brightness in the 30 Angstroms \ passband filter centered at 4308 Angstroms. The white-light flare morphology in the best-observed flares displays a double ``footpoint'' character, establishing a close relationship with the compact magnetic flux tubes involved with both hard and soft X-ray emissions. The ``footpoint'' brightnesses may vary independently with time. We describe the data in the context of the soft and hard X-ray observations simultaneously carried out on board the Yohkoh satellite, emphasizing energetics and timing.
- Publication:
-
Publications of the Astronomical Society of Japan
- Pub Date:
- October 1992
- Bibcode:
- 1992PASJ...44L..77H
- Keywords:
-
- Solar Atmosphere;
- Solar Flares;
- X Ray Telescopes;
- Japanese Spacecraft;
- Spaceborne Astronomy;
- Solar Physics;
- SUN: ACTIVITY;
- SUN: FLARES;
- SUN: SUNSPOTS;
- WHITE-LIGHT FLARES;
- X-RAYS