PSR J0737-3039

PSR J0737−3039

Artist's impression. The objects are not shown to scale: if they were depicted as the size of marbles, they would be 225 m (750 ft) apart. See also MPEG animation (2.4 MB)
Observation data Epoch J2000      Equinox J2000
Constellation	Puppis
Right ascension	07h 37m 51.247s
Declination	−30° 39′ 40.74″
Characteristics
Spectral type	Pulsar
Variable type	None
Astrometry
Distance	3200–4500 Ly (1150 parsecs)
Details
Mass	1.338 M☉
Rotation	22.699379308848 ms

PSR J0737−3039 is the only known double pulsar. It consists of two neutron stars emitting electromagnetic waves in the radio wavelength in a relativistic binary system. The two pulsars are known as PSR J0737−3039A and PSR J0737−3039B. It was discovered in 2003 at Australia's Parkes Observatory by an international team led by the radio astronomer Marta Burgay during a high-latitude pulsar survey.

A pulsar is a neutron star which produces pulsating radio emission due to a strong magnetic field. A neutron star is the ultra-compact remnant of a massive star which exploded as a supernova. Neutron stars have a mass bigger than our sun, yet are only a few kilometers across. These extremely dense objects rotate on their axes, producing focused electromagnetic waves which sweep around the sky in a lighthouse effect at rates that can reach a few hundred pulses per second.

PSR J0737−3039 is the only known system containing two pulsars – thus a 'double pulsar' system. The object is similar to PSR B1913+16, which was discovered in 1974 by Taylor and Hulse, and for which the two won the 1993 Nobel Prize in Physics. Objects of this kind enable precise testing of Einstein's theory of general relativity, because the precise and consistent timing of the pulsar pulses allows relativistic effects to be seen when they would otherwise be too small. Most such binary systems are thought to consist of one pulsar and one neutron star; J0737−3039 is the first case where both components are known to be not just neutron stars but pulsars.

The orbital period of J0737−3039 (2.4 hours) is the shortest yet known for such an object (one-third that of the Taylor-Hulse object), which enables the most precise tests yet. In 2005, it was announced that measurements had shown an excellent agreement between general relativity theory and observation. In particular, the predictions for energy loss due to gravitational waves appear to match the theory.