- Quasi-periodic oscillations: rapid varibility in the light-curves of low-mass X-ray binaries (and some other objects)
- Centroid frequency and intensity of oscillations depends on state of source, as plotted on a "colour" diagram
- QPO offer insight into the accretion process in compact objects
Low Mass X-ray Binaries
EXOSAT's unique orbit allowed short-period X-ray binaries to be studied continuously over many cycles.
Coupled with the high sensitivity and good time resolution of the ME detector, this allowed the light curves to be studied in unprecedented detail .
This ME light curve of the transient EXO0748-67 shows data spanning more than 3 complete orbital cycles, with no interruption. Note the complexity of the light curve.