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Investigating the low-frequency stability of BiSON's resonant scattering spectrometers

Davies, Guy R. (2011)
Ph.D. thesis, University of Birmingham.

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The main focus of the thesis is the study of low-degree low-frequency solar p modes from the analysis of high-resolution power spectra generated from 20 years of high-quality data collected by the Birmingham Solar Oscillations Network (BiSON) Resonant Scattering Spectrometers (RSS). To that end we present a novel model of the RSS and its observations that allows for the determination of a significant improvement in calibration for ground-based Sun-as-a-star Doppler velocity observations. We show that the previously neglected multiple scattering in the RSS vapour cell is significant and demonstrate its impact on the spatial weighting to the solar disk, combining the new instrumental weighting with a detailed treatment of terrestrial atmospheric effects and a model of the solar surface velocity field. The resulting simulation allows for the development of a new and successful correction for differential atmospheric extinction generating up to a 25% increase in the signal-to-noise ratio at low frequencies (0.8 to 1.3 mHz). The improvement in signal to noise allows for the detection of low-frequency p modes with small associated errors in frequency and together with the fitting of mode structure, produces estimates of mode linewidth and power. Over the frequency range 972 to 1850 microHz we find the exponent of the frequency-linewidth dependence to be 7.5(0.4).

Type of Work:Ph.D. thesis.
Supervisor(s):Elsworth, Yvonne and Chaplin, William J.
School/Faculty:Colleges (2008 onwards) > College of Engineering & Physical Sciences
Department:School of Physics and Astronomy
Subjects:QB Astronomy
QC Physics
Institution:University of Birmingham
ID Code:1609
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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