Electric Currents and Magnetic Shear Variations during Some Flares of M- and X-Class
Abstract
We study the magnetic field evolution during flares of M and X-class using overlays of cotemporal halpha filtergrams and magnetograms.Significant decrease in the area-averaged magnetic shear was found in some cases around the flare onset-time, increasing subsequently as the flare progressed. However, the changes were less pronounced for relatively smaller M-class flares. Strong Lorentz forces were found to exist at the photosphere, acting against the observed motions of sunspots. Extrapolated potential field indicated presence of a magnetic null at the upper chromosphere/lower coronal height, directly above a large Halpha flare.
- Publication:
-
IAU Colloq. 153: Magnetodynamic Phenomena in the Solar Atmosphere - Prototypes of Stellar Magnetic Activity
- Pub Date:
- 1996
- DOI:
- 10.1007/978-94-009-0315-9_125
- Bibcode:
- 1996mpsa.conf..533A
- Keywords:
-
- solar flares;
- shear;
- currents