Nonlinear MHD waves in a Prominence Foot

Abstract

We study nonlinear waves in a prominence foot using 2.5D MHD model motivated by recent high-resolution observations with Hinode/SOT in Ca~II emission of a prominence on October 10, 2012 showing highly dynamic small-scale motions in the prominence material. Observations of H$\alpha$ intensities and of Doppler shifts show similar propagating fluctuations. However the optically thick nature of the emission lines inhibits unique quantitative interpretation in terms of density. Nevertheless, we find evidence of nonlinear wave activity in the prominence foot by examining the relative magnitude of the fluctuation intensity ($\delta I/I\sim \delta n/n$). The waves are evident as significant density fluctuations that vary with height, and apparently travel upward from the chromosphere into the prominence material with quasi-periodic fluctuations with typical period in the range of 5-11 minutes, and wavelengths $\sim <$2000 km. Recent Doppler shift observations show the transverse displacement of the propagating waves. The magnetic field was measured with THEMIS instrument and was found to be 5-14 G. For the typical prominence density the corresponding fast magnetosonic speed is $\sim$20 km s${}^{-1}$, in qualitative agreement with the propagation speed of the detected waves. The 2.5D MHD numerical model is constrained with the typical parameters of the prominence waves seen in observations. Our numerical results reproduce the nonlinear fast magnetosonic waves and provide strong support for the presence of these waves in the prominence foot. We also explore gravitational MHD oscillations of the heavy prominence foot material supported by dipped magnetic field structure.

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• SDO/AIA Observations of Large-Amplitude Longitudinal Oscillations in a Solar Filament
• Prominence seismology using small amplitude oscillations
• Propagating Waves Transverse to the Magnetic Field in a Solar Prominence
• MHD waves in two-dimensional prominences embedded in coronal arcades
• Plasma diagnostic in eruptive prominences from SDO/AIA observations at 304 Å
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• Synthetic hydrogen spectra of prominence oscillations

Cited by in corpus (7)

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• Subarcsecond Bright Points and Quasi-periodic Upflows Below a Quiescent Filament Observed by the IRIS
• Interaction of solar jets with filaments: Triggering of large-amplitude filament oscillations
• Fast Magnetosonic Waves and Flows in a Solar Prominence Foot: Observations and Modeling
• Exploration of long-period oscillations in an H$\alpha$ prominence
• Nonlinear Fast Magnetosonic Waves in Solar Prominence Pillars
• Shock-Cloud Interaction in the Solar Corona