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

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.

References in corpus (3)

• Observing the fine structure of loops through high resolution spectroscopic observations of coronal rain with the CRISP instrument at the Swedish Solar Telescope
• Chromospheric and Coronal Observations of Solar Flares with the Helioseismic and Magnetic Imager
• Intensity enhancement of O VI ultraviolet emission lines in solar spectra due to opacity

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• Dynamics of coronal rain and descending plasma blobs in solar prominences: II. partially ionized case
• IRIS Observations of the Mg II h & k Lines During a Solar Flare
• Modeling Mg II during Solar Flares. II. Non-equilibrium Effects
• Two-dimensional simulations of coronal rain dynamics. I. Model with vertical magnetic field and an unbounded atmosphere
• Diagnostic of Homologous Solar Surge Plasma as observed by IRIS and SDO