O'Kane, Jennifer Rose;
(2022)
The Formation and Eruption of Stealth Coronal Mass Ejections.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
Coronal mass ejections (CMEs) drive major space weather events, with the potential to adversely affect the near-Earth environment. Although CMEs can typically be identified using low coronal signatures such as solar flares, filament eruptions, and coronal dimmings, a type of CME with no apparent coronal signature was observed in 2009. The source region of these ‘stealth’ CMEs is difficult to identify and they are potentially geoeffective, making them particularly hazardous. In this thesis, I investigate the initiation and evolution of stealth CMEs using a variety of advanced image-processing techniques and magnetic field modelling. I identified faint signatures associated with the stealth CMEs that are comparable to the low-coronal signatures of classical CMEs, confirming that the same physical processes are taking place for these events. An examination of the global and local magnetic field configuration of the stealth CMEs then enabled me to quantify the evolution of the magnetic field before and after the eruptions, and show how the erupting structures were ultimately deflected into the heliosphere. Finally, I tracked the initial evolution of stealth CMEs and found that they do not typically exhibit the classic three-phase kinematic profile often observed for CMEs, instead evolving via a two-phase velocity profile in which their velocity slowly increases to the background solar wind speed. However, it was not possible to distinguish between the different models proposed to drive the eruptions, suggesting that these events do not typically have one specific driver. This work shows that stealth CMEs do exhibit very faint low coronal signatures, and that while difficult due to the weak magnetic field, modelling of these events is vital to investigate and understand their evolution. Further, it is necessary to have multi-viewpoint and multi-wavelength observation in order to predict and understand these events for future space weather forecasting.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | The Formation and Eruption of Stealth Coronal Mass Ejections |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2022. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics UCL > Provost and Vice Provost Offices > UCL BEAMS UCL |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10143966 |
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