A computer simulation showing how a pulsar’s magnetic field might result in multiple hot spots in one hemisphere. Image: Goddard Space Flight Center
A modest X-ray telescope aboard the International Space Station has provided the first accurate measurements of an isolated neutrons star’s size and mass. Taking advantage of how the concentrated gravity of massive stellar remnants bends light, the researchers even managed to peer beyond the target’s visible face to track the movement of million-degree hot spots across its surface.
“From its perch on the space station, NICER is revolutionising our understanding of pulsars,” said Paul Hertz, astrophysics division director at NASA Headquarters in Washington. “Pulsars were discovered more than 50 years ago as beacons of stars that have collapsed into dense cores, behaving unlike anything we see on Earth. With NICER we can probe the nature of these dense remnants in ways that seemed impossible until now.”
When stars like the Sun run out of nuclear fuel, fusion stops, gravity takes over and cores collapse to form slowly cooling white dwarf stars. But when much more massive stars burn out, gravity is strong enough to crush core material beyond white dwarf densities, producing neutron stars just a few ...