B1508+55 is a spinning neutron star, or pulsar, currently located approximately 7,700 light-years from Earth. Using the Very Long Baseline Array Telescope, scientists found both its speed and position by measuring the powerful beams of radio waves it emits. They then calculated its trajectory across the sky (see image) and determined that it was born out of the supernova explosion some two and a half million years ago of a giant star in the constellation Cygnus. "We know that supernova explosions can give a kick to the resulting neutron star, but the tremendous speed of this object pushes the limits of our current understanding," says Shami Chatterjee of the National Radio Astronomy (NRAO) and the Harvard-Smithsonian Center for Astrophysics.
Moving at an impressive clip of more than 1,000 kilometers a second, the pulsar is on track to leave our home galaxy. "Most earlier estimates of neutron-star speeds depended on educated guesses about their distances," remarks Walter Brisken, an NRAO astronomer. "With this one, we have a precise, direct measurement of the distance, so we can measure the speed directly." The results should help astronomers determine what, if any, other processes could be contributing to B1508+55's speed in addition to the initial supernova.