Observations of magnetically driven events in astronomical systems.

Eves, Benjamin Alistair Curtis (2006). Observations of magnetically driven events in astronomical systems. PhD thesis The Open University.

DOI: https://doi.org/10.21954/ou.ro.0000fe57

Abstract

The interaction of magnetic fields with astrophysical plasmas drives many impressive displays of particle acceleration and impulsive energy release. Within the following work we present a brief overview of magnetic reconnection and energy release mechanisms. We then explore these impulsive energy releases in the form of solar flares (Chapter 2), flaring in the X-ray and optical on other stellar types (Chapter 4), and finally we explore the nature of what could be the brightest microquasar known. The RHESSI spectroscopy of flares in the hard X-ray regime confirms the presence of a deviation from the power law nature of the non-thermal flare spectra. These “knees” allow us to test our current knowledge of particle interactions during a flare. The results of this show that the high resolution spectra do not produce an unphysical result in the underlying accelerated electron spectrum. This gives us greater confindence in our current theoretical understanding of energetic particle interaction. Our observations in both the X-ray (Section 4.1) and the optical (Section 4.2) reveal, as expected, that the flare stars observed were mid M-dwarf stars and cool red dwarfs. Finally we come to the case of 1RXS J 162848.1-415241, possibly the brightest microquasar known to date. As it turns out it is probably not a microquasar at all but more likely is another example of magnetic field interaction, a many spotted RS CVn System. Overall we see magnetically driven events producing some of the most violent energy outburst in the galaxy, and have taken a few steps forward towards a better understanding of the underlying nature of both the events themselves and the objects on which they play out.

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