Two rivers of hot gas are siphoned onto the surface of a neutron star (the collapsed remains of a dead star) in this illustration. Neutron stars pack roughly the mass of our Sun into an area about 10 miles (6 kilometers) across. The gravity at the neutron star’s surface is about 100 trillion times stronger than the gravitational pull on Earth’s surface. Under those conditions, the captured gas accelerates to millions of miles per hour, releasing tremendous energy and radiation when it hits the neutron star’s surface. Because these sources of light emit primarily X-rays, they are known as ultra-luminous X-ray sources (ULXs), and are visible by telescopes like NASA’s NuSTAR (the Nuclear Spectroscopic Telescope Array).
The neutron star’s twisted magnetic field lines are illustrated in green. Some scientists hypothesize that strong magnetic fields like the ones produced by neutron stars can distort the normal shape of atoms from roughly spherical to elongated, stringy shapes. This may ultimately increase an object’s maximum possible brightness.
Figure A shows the neutron star without magnetic field lines.
NuSTAR launched on June 13, 2012. A Small Explorer mission led by Caltech in Pasadena, California, and managed by JPL for NASA’s Science Mission Directorate in Washington, it was developed in partnership with the Danish Technical University (DTU) and the Italian Space Agency (ASI). The telescope optics were built by Columbia University, NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and DTU. The spacecraft was built by Orbital Sciences Corp. in Dulles, Virginia. NuSTAR’s mission operations center is at the University of California, Berkeley, and the official data archive is at NASA’s High Energy Astrophysics Science Archive Research Center. ASI provides the mission’s ground station and a mirror data archive. Caltech manages JPL for NASA.