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Mass and magnetic field of eruptive solar filaments

Carlyle, J; (2016) Mass and magnetic field of eruptive solar filaments. Doctoral thesis, UCL (University College London). Green open access

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Abstract

I present a method for column density calculation of filament material seen in absorption in EUV wavelengths which utilises satellite data in a quasi-spectroscopic way. First, back-falling material following a particularly large eruption is examined and found to have column densities comparable with pre-eruption filaments (over 10^19 cm^−2), which is surprising since the filament material had been seen to expand by approximately two orders of magnitude. I then highlight morphology seen in the back-falling material consistent with the Rayleigh-Taylor instability (RTi) and estimate a characteristic magnetic field strength from equations governing the instability to be 0.6 G. Bubbles indicative of the RTi can also be seen developing into the bulk of the ejecta before breaking up and falling back. The growth rate of these bubbles is measured, and found to be larger than predicted by previous studies. Simulations of RT-unstable plasma are then conducted to investigate the effect of magnetic field strength on the development of the instability, which indicate that the development of the RTi is slower in plasmas with stronger magnetic fields embedded. When the observed growth rates were compared to that of the simulations, they were found to be a factor of five larger possibly due to outflows impacting the material, or that the material is not in fact stationary as the instability sets in. Finally, the column density calculation is refined by removing the noisy 94 Å channel and then applied to various portions of material involved in two unusual eruptions of an intermediate filament. The total hydrogen mass of the filament is estimated to be M_H = 2.4 × 10^15 g, and over half of this material appears to be lost in the second eruption.

Type: Thesis (Doctoral)
Title: Mass and magnetic field of eruptive solar filaments
Event: UCL (University College London)
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Joint funded by the Max Planck Institute for Solar System Research
Keywords: astrophysics, solar physics, astronomy, space science, plasma physics
UCL classification: UCL > School of BEAMS
UCL > School of BEAMS > Faculty of Maths and Physical Sciences
URI: http://discovery.ucl.ac.uk/id/eprint/1474315
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