Correlations Between Large-Scale Solar Photospheric and Chromospheric Motions, Ca II (K) Emission, and Magnetic Fields

Citation

Simon, George Warren (1963) Correlations Between Large-Scale Solar Photospheric and Chromospheric Motions, Ca II (K) Emission, and Magnetic Fields. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/MH5M-9152. https://resolver.caltech.edu/CaltechETD:etd-10282008-150608

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. As previously reported (2,3), large-scale, principally horizontal, motions have been Observed in the solar photosphere. These motions have a cellular appearance, with the flow proceeding from the center of each "cell" toward the outer boundary, with velocities of 0.3 - 0.5 km/sec. These cells are arranged in a more-or-less regular pattern over the solar surface, with an average cell diameter of 30000 - 35000 km. Cross-correlation measurements Obtained by superposition of velocity plates and Ca II (λ3933) plates show that the K[subscript 232]emission network occurs directly above the boundaries of the velocity cells. Downward velocities of 1.0 - 2.0 km/sec are observed in the wings of Hα ([...]λ = 0.74) and Hβ ([...]λ = 0.4A). These localized motions exist in a network pattern which coincides with the position of the K[subscript 232] emission and the velocity cell boundaries. The lifetime of the K[subscript 232] network has been measured by cross-correlating plates taken at various time intervals, and has a mean life of 17 - 21 hours, in excellent agreement with the findings of Macris (4, 5). Using magnetograph measurements obtained by Howard (6), we find a very high degree of correlation between the positions of weak magnetic fields (1.5 - 15 gauss) and the K[subscript 232] network, the correlation increasing as the field strength increases. These observations suggest that the average solar magnetic field (0.5 - 1.0 gauss) is swept to the cell boundaries by the horizontal currents, and concentrates there in strengths several times greater than the average field. These narrow regions of enhanced field strength could then account for the presence of the K[subscript 232] emission at the cell boundaries, and perhaps also indirectly for the downflow of chromospheric material in this region, as well as the small "dots” of rising material seen at the edges of the downward flowing network which may be spicules seen on the disc. The origin of the "supergranulation" may be related to helium ionization which occurs at a depth of 0.5 - 1.5 10[superscript 4] km in the sun. Most of these results have already been reported (7).

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