The growth and decay of sunspots.
Abstract
Sunspots are formed between supergranules, at junctions in the chromospheric network. Many spots disappear rapidly. However, some large spots enter a phase of slow decay: an annular cell develops, centered on the spot and with a systematic outward velocity directed from the penumbra toward the nearest faculae. This flow forms a moat around the spot swept clear of magnetic field except for magnetic features which migrate from the penumbra to the surrounding network. This phase may persist for several months before the spot is finally destroyed. Throughout this period the sunspot area, and hence its flux, decrease at a constant rate. The evolution of a sunspot is related to subphotospheric convection, with particular emphasis on a model of the slow decay phase which explains the steady decay of magnetic flux.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- October 1974
- DOI:
- 10.1093/mnras/169.1.35
- Bibcode:
- 1974MNRAS.169...35M
- Keywords:
-
- Astronomical Models;
- Convective Flow;
- Magnetic Flux;
- Solar Granulation;
- Solar Magnetic Field;
- Sunspots;
- Decay Rates;
- Energy Transfer;
- Evolution (Development);
- Penumbras;
- Photosphere;
- Solar Flux;
- Time Response;
- Solar Physics