Fastest pulsar so far.

Astrophysicists have discovered the swiftest binary pulsar yet recorded, with a pulse period of 5.362 milliseconds. Only six of the 400 or so known pulsars are in binary star systems, but these are of particular importance to astrophysicists, because their binary nature allows studies of their dynamics.

The principal discoverer of this pulsar, 1855+109, is David Segelstein of Princeton (N.J.) University. He was assisted by Joseph Taylor, Daniel Stinebring and Lloyd Rawley of Princeton and Aleksander Wolszczan of the National Astronomy and lonosphere Center's Arecibo Observatory in Puerto Rico. The pulsar is a relatively close neighbor of ours, lying only 1,500 light-years from earth in the constellation Aquila.

Binary pulsars are believed to consists of a neutron star (the actual pulsar) gravitationally bound to a more ordinary star and orbiting their common center of gravity. PSR 1855 +09 has an orbital period of 12.3 days.

In another binary pulsar development, Shrinivas R. Kulkarni of Caltech in Pasadena reports the discovery of stars that may be the companions of binary pulsars 0655+64 and 0820+02. Studies of the dynamics of pairs like these could lead to determinations of the exact masses of the neutron stars, an important datum for calculatons of the evolution and life histories of these objects. Comparing the timekeeping properties of 1855+09 with those of the fastest pulsar of them all, the 1.6-millisecond 1937+215, could determine whether the universe is pervaded by a background flux of gravitational waves generated by the Big Bang.