The Formation of Sunspots from the Solar Toroidal Field.
Abstract
It is shown that a horizontal magnetic flux tube in an electrically conducting atmosphere is buoyant and will tend to rise. This magnetic buoyancy is large enough to bring an occasional strand of flux from the general solar toroidal field up into the photosphere, if we assume general field densities of a few hundred gauss farther down. Identifying the intersection of such ropes with the photosphere as the source of sunspots, we may deduce several general characteristics of the spots, e.g., east-west orientation, bipolarity, appearance only in low latitudes, migration, reversal of polarity, etc. The linearized static equilibrium equations for a flux tube are developed. With a cooling mechanism, such as that suggested by Biermann (1941), we find from the equilibrium equations that a sunspot group should consist of a diffuse flux tube of 10-100 gauss and 10 km extent in the photosphere, forming eventually a number of cool intense cores of several thousand gauss.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 1955
- DOI:
- 10.1086/146010
- Bibcode:
- 1955ApJ...121..491P