Binary systems are star systems comprising two stars orbiting around their common center of mass in a Keplerian orbit, which means that the two components are bound together by their mutual gravitational attraction. In this image, the binary system consists of a main sequence star like our sun, and a neutron star 1.4 times more massive than the sun.
Credit: Northwestern. Stellar simulation by Vicky Kalogera, Bart Willems and Francesca Valsecchi. Visualization by Matthew McCrory.