circular polarization along the lines of force
*
Plate 4.
(1) Southern spot, showing red components of doublets. Nicol, 29º W. (2) One umbra of northern spot, showing violet components of doublets. Nicol, 29º W. (3) Other umbra of northern spot, showing violet components of doublets. Nicol, 29º W. (4) Same umbra of northern spot, showing red components of doublets. Nicol, 61º E. (5) Spot spectrum without Rhomb or Nicol, showing both components of doublets. Scale: 1 Angstrom 6mm.
illustrating C. G. Abbot (1872-1973 *). “Solar Vortices and Magnetism in Sun Spots.” Report of the Board of Regents, Smithsonian Institution, 1908 (Washington, D. C., 1909): 321-338
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Abbot was a remarkable and highly productive figure; started at MIT as an accident. Did work at the Lick and Mt. Wilson observatories (images in this paper apparently made at the tower telescope at Mt. Wilson).
tags: magnetism; solar vortices; spectra; sun spots; C. G. Abbot (1908)