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Properties of Ellerman Bombs and Implications About Formation Mechanisms

Nelson, CJ (2015) Properties of Ellerman Bombs and Implications About Formation Mechanisms. PhD thesis, University of Sheffield.

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Abstract

Ellerman bombs and surges are studied in this thesis in order that inferences about the formation mechanism of these features can be made. General introductions to the solar atmosphere and relevant observational techniques will be presented in Chapters 1 and 2, respectively. Chapter 3 discusses the properties of small-scale brightenings in the Hα line wings. An automated detection algorithm identifies and tracks bright regions, before a null set of confidently identified Ellerman bombs is isolated and compared to the results of previous researches and the smaller features identified by the algorithm. Chapter 4 then compares numerical simulations of magnetic reconnection to the signatures of 7 Ellerman bombs. Each Ellerman bomb occurs co-spatial to a magnetic bi-pole, six of which exhibit flux cancellation or emergence offering potential evidence that magnetic reconnection is the driver of these features. The properties of 22 Ellerman bombs at the solar limb are inferred in Chapter 5. Two in-depth case studies are presented which highlight the dynamical nature of individual features, including their morphological properties and potential links to the magnetic field. Chapter 6 discusses the physical properties of Moving Magnetic Features, the cancellation rates of which are measured, and how such properties fit into the hypothesised theory of magnetic reconnection as the driver of Ellerman bombs. An algebraic model of magnetic reconnection is employed such that upflow velocities, extension lengths, and local number densities can be derived. The outputs from this model agree well with measurements of Ellerman bombs returned in previous Chapters. Finally, an isolated surge is studied in Chapter 7. The temporal evolution of the line-of-sight magnetic field shows no evidence of magnetic reconnection co-spatial to this surge; however, a blinker forms co-spatially with this feature. This offers compelling evidence that blinkers may be linked to photospheric mass supply.

Item Type: Thesis (PhD)
Keywords: Solar Physics
Academic Units: The University of Sheffield > Faculty of Science (Sheffield) > School of Mathematics and Statistics (Sheffield)
Identification Number/EthosID: uk.bl.ethos.675072
Depositing User: Mr CJ Nelson
Date Deposited: 11 Dec 2015 14:56
Last Modified: 03 Oct 2016 12:19
URI: http://etheses.whiterose.ac.uk/id/eprint/11161

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