This composite shows an artist's impression (center) of a millisecond pulsar and its companion with an insert of the ESA/NASA/ESA Hubble Space Telescope image of the region (upper left). The millisecond pulsar system lies in the globular cluster NGC 6397 in Ara (the Altar). In the Hubble image insert the companion star is marked with an arrow. The artist's impression shows the pulsar (seen in blue with two radiation beams) and its bloated red companion star. Scientists believe that the best explanation for seeing a bloated red star instead of a 'quiet' white dwarf in the system is that the pulsar only recently has been spun up to its current rotation speed of 274 times per second by the gases transferred by the red star. It is the first time such a system has been observed.

Credit: European Space Agency & Francesco Ferraro (Bologna Astronomical Observatory)