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PSR J0737–3039A double radio pulsar system in the southern constellation Puppis and the first such system to be discovered. One component, a 23-millisecond pulsar now known as PSR J0737–3039 A, was discovered in 2003 by an international team of scientists using the 64-meter CSIRO radio telescope at the Parkes Observatory in New South Wales, Australia. At first it was assumed that this pulsar was orbiting a non-pulsing neutron star, but further observations made with the Parkes dish and the 76-meter Lovell radio telescope at the University of Manchester's Jodrell Bank Observatory in Cheshire, England, UK, revealed that the companion, now designated PSR J0737–3039 B, had a detectable slow pulse, rotating once every 2.8 seconds. The two pulsars are an estimated 800 000 kilometers apart and orbit around a common center of mass once every 2.4 hours. By chance the orbit appears edge-on, and each pulsar periodically eclipses the other, allowing researchers for the first time to analyze the physical conditions of a pulsar's magnetosphere or outer atmosphere. It is thought that the double-pulsar system evolved when, following the supernova explosion of the more massive PSR J0737–3039 A and its transformation into a pulsar, a companion star was born and eventually developed into a giant. Material from the giant was accreted on the pulsar by mass transfer, making it spin faster. In time, the giant also exploded as a supernova and it too developed into a pulsar. Powerful gravitational forces are drawing the pulsars closer to each other, and scientists estimate that they will coalesce in 85 million years' time, possibly forming a black hole. Distance: 500–600 pc. See pulsar.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006