Artist's impression of an evolving white dwarf and millisecond pulsar binary system.

Artist's impression of an evolving white dwarf (foreground) and millisecond pulsar (background) binary system. Using the 4.1-meter SOAR Telescope on Cerro Pachón in Chile, part of Cerro Tololo Inter-American Observatory, a Program of NSF's NOIRLab, astronomers have discovered the first example of a binary system consisting of an evolving white dwarf orbiting a millisecond pulsar, in which the millisecond pulsar is in the final phase of the spin-up process. The source, originally detected by the Fermi Space Telescope, is a “missing link” in the evolution of such binary systems.