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A Magnetic Field Strength vs. Temperature Relation in Sunspots

Published online by Cambridge University Press:  03 August 2017

Greg Kopp  and
Douglas Rabin
Greg Kopp
Affiliation:
National Solar Observatory, National Optical Astronomy Observatories, * P.O. Box 26732, Tucson, AZ 85726, U.S.A.
Douglas Rabin
Affiliation:
National Solar Observatory, National Optical Astronomy Observatories, * P.O. Box 26732, Tucson, AZ 85726, U.S.A.

Abstract

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The near infrared presents several new and powerful advantages in the diagnostics of sunspot atmospheres: (1) increased magnetic sensitivity in Zeeman-split lines, (2) increased sensitivity of umbral brightness to temperature, and (3) reduced scattered light and seeing disturbances due to atmospheric turbulence. This has revealed a strong and consistent relationship between sunspot brightness and magnetic field strength.

We have made spatial/spectral observations of sunspots in the highly sensitive (g = 3) Fe I line at λ = 1.5649 μm to compare field strengths with continuum intensities. We find a characteristic but nonlinear relationship between magnetic field strength, B, and brightness temperature, T b , in sunspots. In umbrae there is an approximately linear relation between B 2 and T b .

Keywords

infrared: starsSun: magnetic fieldssunspots
Type
Part 5: Magnetic Fields and Infrared Magnetometry
Information
Symposium - International Astronomical Union , Volume 154: Infrared Solar Physics , 1994 , pp. 477 - 482
Copyright
Copyright © Kluwer 1994 

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