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E. N. Parker (University of Chicago)
The magnetic activity of the Sun, with its terrestrial outreach, is conventionally defined in terms of the larger magnetic features on the surface of the Sun, while the evolution of the large magnetic features is largely determined by their small-scale fibril structure. Unfortunately the individual fibrils can be observed only as unresolved bright blobs. Thus their frequent interactions, their internal structure, and the associated dynamical flows all remain a mystery, which prevents our constructing a definitive dynamical theory of the large-scales and of solar activity in general.
The microscopic world of magnetic fibrils awaits investigation, requiring a suitable telescope system with adaptive optics at an excellent site so as to provide angular resolution of 0.1" or better on a regular basis. The telescope must be of sufficient aperture (~ 4m) to carry on high resolution, high dispersion spectroscopy at rapid cadence to determine the time dependent spatial structure of the gas flows and magnetic fields on the smallest possible scales. It will be important to follow the rapid evolution of the small flux bundle, or fibril, as it first appears through the visible surface somewhere in the interior of a supergranule, and then to follow the resulting magnetic fibril as it is convected into the boundary downdrafts, and ultimately into the junctions of several boundaries. The quiet photosphere, the active photosphere, at both low and high latitudes, the umbra and penumbra of sunspots of all sizes, the ephemeral active regions, the microstructure of all classes of flares, and the microstructure of spicules, surges and prominences are obvious immediate targets for the high resolution telescope. We cannot anticipate what will be seen, but whatever it turns out to be, it will move scientific comprehension well ahead of the present limited conjectural state.
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.