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| Paper: |
Generating Magnetic Fields in Early-type Stars |
| Volume: |
337, The Nature and Evolution of Disks Around Hot Stars |
| Page: |
28 |
| Authors: |
MacGregor, K.B. |
| Abstract: |
Although magnetic fields have been detected in many upper main sequence stars, the physical origins of this magnetism are not well understood. After surveying the magnetic properties of these stars and reviewing some of the arguments for and against a fossil origin for the observed fields, we examine the possibility that they are produced by a hydromagnetic dynamo, operating within the central convective core. We describe model results suggesting that dynamo action can take place in such an environment, but that the high electrical conductivity and large spatial extent of the overlying, stably stratified, radiative envelope are significant obstacles to the emergence of the generated fields at the stellar surface. Advection by internal circulatory flows is, by itself, an ineffective transport mechanism, but the buoyant rise of tube-like concentrations of magnetic flux may, under certain conditions, contribute to bringing the fields from the core to the photosphere. We briefly discuss some alternative models, in which these problems are circumvented by field generation processes that take place closer to the stellar surface. |
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