X‐RAY BURST SOURCES*

Abstract

Current knowledge of sources of X-ray bursts, defined as having rise times of less than a few seconds, durations of a few seconds to a few minutes and a generally regular recurrence pattern, is reviewed. An examination of the galactic distribution of X-ray burst sources, which has been confirmed by SAS-3 rotating modulation collimator observations, reveals that the burst sources are spread along the galactic equator and clustered near low galactic longitudes, unlike the distribution of globular clusters. At least four X-ray burst sources have been associated with steady X-ray sources based on positional coincidence, and it has been found that the X-ray bursts are less intense but harder than steady X-ray emission from these sources. Individual burst sources, including MXB1659-29, which has not been identified with a steady X-ray source, the source in NGC6624 which has been identified with 3U1820-30, MXB1837+05, associated with Ser X-1, three burst sources near the galactic center and the rapid burster MXB1730-335 are briefly discussed.