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arXiv · 1409.0377

The impact of a filament eruption on nearby high-lying cool loops

L. K. Harra·S. A. Matthews·D. M. Long·G. A. Doschek·B. De Pontieu
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Abstract

The first spectroscopic observations of cool Mg II loops above the solar limb observed by NASA's Interface Region Imaging Spectrograph ({\it IRIS}; \cite{IRIS}) are presented. During the observation period IRIS is pointed off-limb allowing the observation of high-lying loops, which reach over 70~Mm in height. Low-lying cool loops were observed by the {\it IRIS} slit jaw camera for the entire 4 hour observing window. There is no evidence of a central reversal in the line profiles and the Mg II h/k ratio is approximately 2. The Mg II spectral lines show evidence of complex dynamics in the loops with Doppler velocities reaching $\pm$ 40 km/s. The complex motions seen indicate the presence of multiple threads in the loops and separate blobs. Towards the end of the observing period, a filament eruption occurs that forms the core of a coronal mass ejection. As the filament erupts, it impacts these high-lying loops, temporarily impeding these complex flows, most likely due to compression. This causes the plasma motions in the loops become blue-shifted and then red-shifted. The plasma motions are seen before the loops themselves start to oscillate as they reach equilibrium following the impact. The ratio of the Mg h/k lines also increases following the impact of the filament.

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L. K. Harra, S. A. Matthews, D. M. Long, G. A. Doschek, B. De Pontieu. 2014-09-01. The impact of a filament eruption on nearby high-lying cool loops. https://doi.org/10.1088/0004-637x/792/2/93

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