Born amid the violence of supernova explosions, neutron stars are the extremely dense endpoints of stars that initially had a mass of more than about ( is the mass of the Sun, about ). During its final collapse, such a star expels most of its material, leaving behind a remnant—a neutron star—packing a typical mass of into a radius of only 10 km. With a density comparable to that of an atomic nucleus, a neutron star provides an extreme environment for fast and violent phenomena: Matter orbiting a neutron star can have a period as short as a millisecond; when it crashes into the star (that is, when it is “accreted”), this matter can be moving at one‐third the speed of light. Because their behavior can vary over readily observable time scales, neutron stars can be rich sources of information about nuclear physics, general relativity and astrophysics.
Skip Nav Destination
Article navigation
February 1999
February 01 1999
New Views of Neutron Stars
Satellites launched in the last ten years have proved to be powerful new tools for studying these compact stellar remnants. With them, astronomers have found remarkable new phenomena and solved several old mysteries.
Physics Today 52 (2), 40–46 (1999);