Sco X-1, discovered in 1962 and later identified with an optical star, V818 Scorpii, 700 parsecs distant, is what astronomers call a Low Mass X-ray Binary ( LMXB), meaning that an analysis of its X-ray emission indicates it is a pair of stars; a late-type ordinary star, and a neutron star ( not a black hole) in orbit around each other with a period of 18.9 hours. Astronomers have used other X-ray data to determine that the light from this system is dominated by the emission from a very hot plasma which can be detected from numerous X-ray 'lines' which it produces, in addition to what is called 'free-free' or 'thermal bremstrahlung' emission caused by charged electrons colliding with protons at high energy and giving off light. A careful analysis of the light shows that there is a constant black body component with a temperature of over 50,000 K ( 2 keV) which is believed to be the surface of the neutron star itself. The lack of 'hard' X-rays with energies above a few keV indicates that this is not a black hole.
Sco X-1 is a variable star with an amplitude from +12.2 at its brightest, to +13.6 at its faintest. During its bright phase, X-ray flares and flickering are commonly observed. Rapid X-ray variability has been seen above a few seconds, but despite several studies, most recently by B. Vaughan from the University of Amsterdam ( Astrophysics Journal, vol. 435, p. 362) in 1994, no firm detection of pulsations in the milli-second range have been conclusively established. Evidently, although this neutron star has an accretion disk and is a powerful X-ray source, it is not a 'Pulsar'. Also, the lack of flickering below 1 second time scales would seem to indicate that the material that falls onto the neutron star's surface comes down rather smoothly, and is not clumpy. Clumps might be expected whenever you have a hot dense plasma interacting with a strong magnetic field.