X-Ray Sources: Sco X-1

The sources of these QPO's vary in an irregular mamer. Fourier analysis reveals that there are regular variations present, but the period of the modulation varies with the intensity of the source. The period varies over a frequency range 2O-4OHz (i.e. 50-25 milliseconds), with the frequency increasing as the source brightens. Because the period is always changing it is called a quasi-periodic oscillation. However, at the brightest levels of source brightness the QPO's disappear completely.

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