Solar Active Regions as a Percolation Phenomenon
Abstract
The appearance of solar active regions is modeled using percolation theory. An attempt is made to bundle all the very complicated magnetic phenomena into two dimensionless parameters. The main parameter is the probability, Pst, that the release and rise of one flux tube stimulates the subsequent release and rise of a neighboring flux tube. A second parameter measures the lifetime of flux once it has arrived at the surface. This hypothesis is used to reproduce several properties of the distribution of active regions on the sun. (1) The active regions persist for a long time. Magnetic flux emerges mostly where there is flux already. (2) There are persistent empty regions, reminiscent of coronal holes. (3) The dependence on Pst is that of a phase transition. (4) The size distribution of the active regions is close to exponential, as observed.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 1992
- DOI:
- 10.1086/171278
- Bibcode:
- 1992ApJ...390..280W
- Keywords:
-
- Magnetohydrodynamics;
- Percolation;
- Solar Activity;
- Solar Magnetic Field;
- Dynamo Theory;
- Magnetic Flux;
- Solar Cycles;
- Stellar Models;
- Solar Physics;
- MAGNETOHYDRODYNAMICS: MHD;
- SUN: ACTIVITY;
- SUN: MAGNETIC FIELDS