Energy storage in solar loops by footpoint motions
Abstract
The amount of stored magnetic energy in an arcade, sheared by footpoint motions due to the relative velocity of young and recurrent sunspot groups (RSG), has been evaluated in the force-free-field approximation. The relative velocity (Delta v) between young and RSG and the time scales during which this Delta v lasts have been estimated from the analysis of sunspot data reported in the Greenwich Photoheliograhic Results for the years 1874-1976. Using shearing times from 86,000-260,000 sec and Delta v of 2940-3470 cm/sec, it is found that the stored energy may be (1-1000) x 10 to the 30th ergs. The consequences of these results, concerning the phase of energy build-up for loop heating and for transients are discussed.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- April 1989
- Bibcode:
- 1989A&A...214..369Z
- Keywords:
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- Coronal Loops;
- Force-Free Magnetic Fields;
- Magnetic Energy Storage;
- Sunspots;
- Angular Velocity;
- Photosphere;
- Solar Magnetic Field;
- Velocity Distribution;
- Solar Physics