Astronomy: Hale and Luckey Some Vortex Experiments Bearing on the Nature

As the result of an eruption, or some other cause tending to produce rapid convection, a gaseous column moves upward from within the sun toward the surface of the photosphere. Vortex motion is initiated by differences in velocity of adjoining surfaces or by irregularities of structure and is maintained by convection. The circulation in the vortex is vertically upward and then outward along the photosphere, as in a terrestrial tornado. Expansion produces cooling at the center of the vortex, and a comparatively dark area (the umbra) results. As in Harker's electric furnace experiments, a rapid flow of negative ions sets in toward the cooler gases at the center from the hotter gases without. These ions, whirled in the vortex, produce a magnetic field, plainly indicated by the widened and resolved lines of the sun-spot spectrum. Hitherto we have assumed the spot to be single. The typical sun-spot group is double, though either or both of the principal members may be replaced by several smaller spots. The axis of the group makes a small angle with the solar equator, and the magnetic polarities of the preceding and following members are opposite in sign. Such a group may result from the tendency of any columnar vortex to turn up toward the photosphere, thus forming a semi-circular vortex ring. A secondary vortex, caused by the influence of the low-lying spot vortex on the gases of the solar atmosphere above it, partially determines the structure of the hydrogen flocculi, which are drawn inward at high levels, then downward and outward at the upper levels of the spot vortex. The hydrodynamic structure thus developed may be more or less modified by the influence of the spot magnetic field on the trajectories of the moving ions within it.