A stellar X-ray source showing violent and random changes in their emission. X-ray bursters were discovered with the Dutch satellite ANS in 1976. The bursts may last for several days and may recur, but are not periodic. A rapid burster repeats at intervals no longer than 10 seconds. The numbers known are counted in tens; most are in the galactic plane though some are in globular clusters. The generally accepted model is that of an interacting binary system, similar to a nova, except that accretion takes place on to a neutron star rather than a white dwarf, and the material transferred is predominantly helium rather than hydrogen. The X-ray burst occurs when the accumulation of accreted material reaches the critical temperature and density to detonate a thermonuclear explosion. See also: X-ray astronomy.