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Paper: |
Magnetic Fields on Cool Stars |
Volume: |
448, 16th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun |
Page: |
255 |
Authors: |
Reiners, A. |
Abstract: |
Magnetic fields are an important ingredient to cool star physics,
and there is great interest in measuring fields and their geometry
in order to understand stellar dynamos and their influence on star
formation and stellar evolution. During the last few years, a large
number of magnetic field measurements became available. Two main
approaches are being followed to measure the Zeeman effect in cool
stars; 1) the measurement of polarized light, for example to produce
magnetic maps, and 2) the measurement of integrated Zeeman
broadening to measure the average magnetic field strength on the
stellar surface. This article briefly reviews the two methods and
compares results between them that are now available for about a
dozen M-type stars. It seems that we see a great variety of magnetic
geometries and field strengths with typical average fields of a few
kG in active M-type stars. The interpretation of geometries,
however, has not yet led to a clear picture of magnetic dynamos and
field configuration, and work is needed on more observational data
but also on the fundamental understanding of our measurements. |
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