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Mass Estimates of Rapidly Moving Prominence Material From High-Cadence EUV Images  

David Williams   Submitted: 2013-01-17 16:44

We present a new method for determining the column density of erupting filament material using state-of-the- art multi-wavelength imaging data. Much of the prior work on filament/prominence structure can be divided between studies that use a polychromatic approach with targeted campaign observations, and those that use synoptic observations, frequently in only one or two wavelengths. The superior time resolution, sensitivity and near-synchronicity of data from the Solar Dynamics Observatory's Advanced Imaging Assembly allow us to combine these two techniques using photo-ionisation continuum opacity to determine the spatial distribution of hydrogen in filament material. We apply the combined techniques to SDO/AIA observations of a filament which erupted during the spectacular coronal mass ejection on 2011 June 07. The resulting ''polychromatic opacity imaging'' method offers a powerful way to track partially ionised gas as it erupts through the solar atmosphere on a regular basis, without the need for co-ordinated observations, thereby readily offering regular, realistic mass-distribution estimates for models of these erupting structures.

Authors: Williams, D. R., Baker, D., van Driel-Gesztelyi, L.
Projects: SDO-AIA

Publication Status: Accepted
Last Modified: 2013-01-22 10:40
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Evidence from EIS for axial filament rotation before a large flare  

David Williams   Submitted: 2009-02-04 00:02

In this article, we present observations made with the Extreme-ultraviolet Imaging Spectrometer (EIS) on-board the Hinode solar satellite, of an active region filament in the He II emission line at 256.32 ?. The host active region (AR 10930) produces an X-class flare during these observations. We measure Doppler shifts with apparent velocities of up to 20 km s-1, which are antisymmetric about the filament length and occur several minutes before the flare?s impulsive phase. This is indicative of a rotation of the filament, which is in turn consistent with expansion of a twisted flux rope due to the MHD helical kink instability. This is the first time that such an observation has been possible in this transition-region line, and we note that the signature observed occurs before the first indications of pre-flare activity in the GOES solar soft X-ray flux, suggesting that the filament begins to destabilise in tandem with a reorganistation of the local magnetic field. We suggest that this expansion is triggered by the decrease of magnetic tension around, and/or total pressure above, the filament.

Authors: Williams, D. R., Harra, L. K., Brooks, D. H., Imada, S., Hansteen, V. H.
Projects: Hinode/EIS

Publication Status: Accepted for publication in PASJ (Vol. 61, No. 3, June 2009)
Last Modified: 2009-02-04 08:44
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Mass Estimates of Rapidly Moving Prominence Material From High-Cadence EUV Images
Evidence from EIS for axial filament rotation before a large flare

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