Case Study: Solar Coronal Loops as Self-Channeled Proton Beams I

Abstract

Solar coronal loops are spectacular luminous arcs that extend upward from the surface of the Sun up to altitudes of 400 megameters, which is 30 times the diameter of the Earth. The beam diameter is about one megameter, when observed at the H_α wavelength, but 0.3 megameter at X-ray wavelengths. How can that be? What are they? Are they charged particle beams? If so, what kind of particle are they? And what is the particle energy, what is the beam current? Just how much power is involved in one loop? In this chapter we attempt to answer all these questions, and the next chapter poses several other questions. We refer to solar coronal loops, but the main properties of loops possibly apply also to fibrils, coronal jets, streamers, threads, filamentary structures in prominences, to a host of thread-like structures in the solar atmosphere, and to solar-like stars.1