Numerical Simulation of Solar Coronal Magnetic Fields
Abstract
Many aspects of solar activity are believed to be due to the stressing of the coronal magnetic field by footpoint motions at the photosphere. We present the results of a fully spectral numerical simulation which, to our knowledge, is the first 3-d time dependent simulation of footpoint stressing in a geometry appropriate for the corona. We consider an arcade that is initially current-free and impose a smooth footpoint motion that produces a twist in the field of approximately 2 pi. We then fix the footpoints and follow the evolution until the field relaxes to another current-free state. We see no evidence for any instability, either ideal or resistive and no evidence for current sheet formation. The most striking feature of the evolution is that in response to photospheric motions, the field expands rapidly upward to minimize the stress. The expansion has two important effects. First, it suppresses the development of dips in the field that could support dense, cool material. For the motions that we assume, the magnetic field does not develop a geometry suitable for prominence formation. Second, the expansion inhibits ideal instabilities such as kinking. Our results indicate that simple stearing of a single arcade is unlikely to lead to solar activity such as flares or prominences. We discuss effects that might possibly lead to such activity.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 27, 1990
- Accession Number
- ADA227283
Entities
People
- Russell B. Dahlburg
- Spiro K. Antiochos
- T. A. Zang
Organizations
- United States Naval Research Laboratory