by Vladimir LIPUNOV, Cand. Sc. (Phys. & Math.), P. K. Sternberg State Institute of Astronomy of Moscow State University
All the way back in 1932 the Soviet physicist Lev Landau (Nobel prize, 1962) postulated the existence of superdense stars, or giant atomic nuclei commensurate with the sun in mass. Landau had published his work just before the discovery of the neutron. And a year later, with the neutron already discovered, the American astronomers W. Baade and F. Zwicky hypothesized that the bursts of supernovas resulted from the disastrous compression (collapse) of a normal star into a superdense state. Superdense stars embody the final stage in the lifetime of ordinary stars with the initial mass of their nucleus above 1.4 MΘ (MΘ denoting solar mass). With the pool of its nuclear fuel exhausted, a star collapses: its outer layers blow off on a supernova explosion at an immense velocity of about 10,000 km/s, and the inner ones plunge toward the core under the effect of the gravitational pull (drag), for there is no longer the counteracting gas pressure force to prevent that. Within split seconds the star's inner layers contract to a 100,000th part of the original mass, and its volume shrinks ~1015fold. The mean density increases as much over and above the nuclear density. From that moment on the gravitational forces working to compress the star will be counterbalanced by nuclear forces. Atomic nuclei in this star will be tightly pushed together. Knowing the dimensions of atomic nuclei (10-13 cm) and their number, astrophysicists have determined the radius of a star like that (- 10 km). M. Baade and F. Zwicky named such celestial bodies neutron stars. That's how the ancient science of astronomy witnessed a truly revolutionary event in the early 1930s as theoretical physicists predicted a new class of objects in the universe.
Neutron stars were identified only 35 years after. In July 1967 a team of British radio astronomers under Antony Hewish discovered radio ... Read more