University of Leicester
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X-ray spectral studies of scorpius x-1.

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posted on 2015-11-19, 08:49 authored by Richard Griffiths
The thesis describes the design, testing and flight results from two Skylark rocket experiments which were primarily intended to make high-resolution searches for line emission in the X-ray spectrum of Scorpius X-1. The observations of Sco X-1, up to the end of 1968, over all frequencies of the electromagnetic spectrum, are summarised, together with the astrophysical models of the object and their implications for the X-ray spectrum. The decision to search for line emission in the spectrum arose from the need to establish whether the X-rays are of bremsstrahlung or synchrotron origin. The first Bragg crystal spectrometer to study a non-solar X-ray source was flown on a sun-pointing British Skylark from Woomera in March 1970, and an improved experiment of the same kind was flown on an E.S.R.O. Skylark from Sardinia in March 1971. The payloads were the first to employ roll stabilisation on an X-ray star using proportional detectors. The proportional detector experiments confirmed the bremsstrahlung nature of the X-ray emission, while the high-resolution spectrometers established that Doppler-broadened Fe XXV line emission is at least an order of magnitude less intense than is expected from a low-density plasma. Fluctuations in the X-ray intensity were observed on 1 minute time scales, as found in the optical data. A summary is given of contemporary work on Sco X-1, and the absence of narrow line emission is found to be consistent with those models of the X-ray source which envisage a high-density, toroidal plasma in orbit around a central white-dwarf or neutron star.


Date of award


Author affiliation

College of Medicine, Biological Sciences and Psychology

Awarding institution

University of Leicester

Qualification level

  • Doctoral

Qualification name

  • PhD



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