Einstein’s Theory of Relativity, Critical for GPS, Seen in Distant Stars

The intriguing system known as 4U 1916-053.

The intriguing system known as 4U 1916-053 contains two stars in a remarkably close orbit. One is the core of a star that has had its outer layers stripped away, leaving a star that is much denser than our Sun. The other is a neutron star, an even denser object created when a massive star collapses in a supernova explosion. The neutron star (grey) is shown in this artist's impression at the center of a disk of hot gas pulled away from its companion (white star on left). (Image: Spectrum: N. Trueba et al via NASA / CXC / University of Michigan, Illustration: M. Weiss via NASA / CXC)