A study of the contrast of sunspots from photometric images |
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Authors: | John G. Beck Gary A. Chapman |
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Affiliation: | (1) San Fernando Observatory, Department of Physics and Astronomy, California State University, 91330 Northridge, CA, USA |
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Abstract: | The thermal contrast , and the umbra-penumbraAu/Ap, were calculated for 63 sunspots of various sizes and morphologies. Contrary to the assumptions of the PSI model, andAu/Ap were found to be quite variable. The values of ranged from 0.1807 to 0.4266;Au/Ap ranged from 0.0089 to 0.4899. The values of andAu/Ap correlated well (r = 0.6018;p<0.005) and the regression for andAu/Ap was obtained: = (0.220 ± 0.016) + (0.340 ± O.06)Au/Ap. The values of andAu/Ap were then compared with complexity ratings, magnetic field strength, time, and . The quantities andAu/Ap were found to be independent of the complexity, magnetic field strength, and time factors. The correlation between andAu/Ap lead to the proposed division of into an umbral thermal contrast u, and a penumbral thermal contrast p. These values were calculated from the photometric data: u = 0.57 ± 0.01 and p = 0.26 ± 0.006. |
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