Helioseismic and Magnetic Imager observations of linear polarization from a loop prominence system

Abstract

White-light observations by the Solar Dynamics Observatory's Helioseismic and Magnetic Imager of a loop-prominence system occurring in the aftermath of an X-class flare on 2013 May 13 near the eastern solar limb show a linearly polarized component, reaching up to $\sim$20% at an altitude of $\sim$33 Mm, about the maximal amount expected if the emission were due solely to Thomson scattering of photospheric light by the coronal material. The mass associated with the polarized component was 8.2$\times$10${}^{14}$ g. At 15 Mm altitude, the brightest part of the loop was 3(+/-0.5)% linearly polarized, only about 20% of that expected from pure Thomson scattering, indicating the presence of an additional unpolarized component at wavelengths near Fe I (617.33 nm), probably thermal emission. We estimated the free electron density of the white-light loop system to possibly be as high as 1.8$\times$10${}^{12}$ cm${}^{-3}$.

9 pages, 5 figures

References in corpus (2)

• RHESSI Line and Continuum Observations of Super-hot Flare Plasma
• Chromospheric and Coronal Observations of Solar Flares with the Helioseismic and Magnetic Imager

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