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S. M. White (University of Maryland)
Coronal magnetic fields are implicated in most active phenomena in the Sun's corona but their measurement is a difficult problem. While a selection of coronal magnetic field lines can be seen in soft X-ray and EUV images, they contain no information on magnetic field strength. Magnetic field measurements in the lower solar atmosphere are a priority for the Solar-B and Solar Dynamics Observatory missions, but they will not measure coronal magnetic fields directly, relying instead on extrapolations of surface field measurements. On the other hand, radio measurements can determine the magnetic field strength in the corona, including regions seen against the solar disk, in a straightforward fashion at least for field strengths larger than a few hundred gauss. This talk will discuss progress in the established technique of measuring active region magnetic fields through their gyroresonance emission at centimeter wavelengths and prospects for vastly improved measurements with the Frequency Agile Solar Radiotelescope. Such measurements can be valuable for establishing the validity of extrapolations and, e.g., resolving the 180 degree ambiguity of vector magnetic field measurements, in addition to their direct diagnostic power. The basis of the method and examples of its application will be discussed, and comparison with other approaches will be made. This work is supported by the NSF and NASA.
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.