Observations of Thomson scattering from a loop-prominence system

Abstract

We describe observations of the white-light structures in the low corona following the X8.2 flare SOL2017-09-10, as observed in full Stokes parameters by the Helioseismic and Magnetic Imager (HMI) of the Solar Dynamics Observatory. These data show both bright loops and a diffuse emission region above them. We interpret the loops as the white-light counterpart of a classical loop-prominence system, intermediate between the hot X-ray loops and coronal rain. The diffuse emission external to the loops is linearly polarized and has a natural interpretation in terms of Thomson scattering from the hot plasma seen prior to its cooling and recombination. The polarimetric data from HMI enable us to distinguish this contribution of scattering from the HMI pseudo-continuum measurement, and to make a direct estimation of the coronal mass in the polarized source. For a snapshot at 16:19~UT, we estimate a mass $8\times 10^{14}$~g. We further conclude that the volumetric filling factor of this source is near unity.

13 pages, 6 figures, Accepted in ApJ

References in corpus (5)

• Magnetic Reconnection During the Post-Impulsive Phase of a Long-Duration Solar Flare: Bi-Directional Outflows as a Cause of Microwave and X-ray Bursts
• Microwave Spectral Imaging of an Erupting Magnetic Flux Rope: Implications for the Standard Solar Flare Model in Three Dimensions
• Energetic Electron Distribution of the Coronal Acceleration Region: First results from Joint Microwave and Hard X-ray Imaging Spectroscopy
• Spectropolarimetric Insight into Plasma-Sheet Dynamics of a Solar Flare
• Signatures of Helium continuum in cool flare loops observed by SDO/AIA

Cited by in corpus (1)

• An overview of HMI off-disk flare observations