PSR B1913+16

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PSR B1913+16
Observation data
Epoch B1950.0      Equinox B1950.0
Constellation Aquila[1]
Right ascension 19h 13m 12.4655s
Declination 16° 01′ 08.189″
Distance 21,000 ly
(6400 pc)
Mass 1.441 M
Rotation 59.02999792988 ms
Orbital decay of PSR B1913+16.[3] The data points indicate the observed change in the epoch of periastron with date while the parabola illustrates the theoretically expected change in epoch according to general relativity.

PSR B1913+16 (also known as PSR J1915+1606 and PSR 1913+16) is a pulsar (a radiating neutron star) which together with another neutron star is in orbit around a common center of mass, thus forming a binary star system. PSR 1913+16 was the first binary pulsar to be discovered. In 1974 it was discovered by Russell Alan Hulse and Joseph Hooton Taylor, Jr., of the University of Massachusetts Amherst. Their discovery of the system and analysis of it earned them the 1993 Nobel Prize in Physics "for the discovery of a new type of pulsar, a discovery that has opened up new possibilities for the study of gravitation."[4]

The system is also called the Hulse–Taylor binary pulsar after its discoverers.




The pulses from the pulsar arrive 3 seconds earlier at some times relative to others, showing that the pulsar’s orbit is 3 light-seconds across, approximately the diameter of the Sun. Since this is a binary system, the masses of the two neutron stars can be determined, and they are each around 1–3 times the mass of the Sun. Observations have shown that the pulsar’s orbit is gradually contracting, due to the emission of energy in the form of Gravitational Waves, as predicted by Einstein’s theory of general relativity, causing the pulsar to reach periastron slightly early. Also, periastron advances 4º per year in longitude due to the gravitational field (thus the pulsar’s periastron moves as far in a day as Mercury’s moves in a century).

Star system[edit]



The orbit has decayed since the binary system was initially discovered, in precise agreement with the loss of energy due to gravitational waves predicted by Einstein's general theory of relativity.[2][5][6][7] The ratio of observed to predicted rate of orbital decay to be 0.997±0.002.[7] The total power of the gravitational radiation (waves) emitted by this system presently, is calculated to be 7.35 × 1024 watts. For comparison, this is 1.9% of the power radiated in light by our own Sun. (Another comparison is that our own Solar System radiates only about 5000 watts in gravitational waves, due to the much larger distances and orbit times, particularly between the Sun and Jupiter).

With this comparatively large energy loss due to gravitational radiation, the rate of decrease of orbital period is 76.5 microseconds per year, the rate of decrease of semimajor axis is 3.5 meters per year, and the calculated lifetime to final inspiral is 300,000,000 years.[2][7]

  • Mass of companion: 1.387 MSun
  • Total mass of the system: 2.828378(7) MSun
  • Orbital period: 7.751938773864 hr
  • Eccentricity: 0.6171334
  • Semimajor axis: 1,950,100 km
  • Periastron separation: 746,600 km
  • Apastron separation: 3,153,600 km


In popular culture[edit]

Science fiction writer Arthur C. Clarke offhandedly speculated, in his television series Mysterious World, that this pulsar was the Star of Bethlehem. He ended the 12th episode with the line, "How romantic if even now we can hear the dying voice of the star which heralded the Christian era."[citation needed]

See also[edit]


  4. ^ "The Nobel Prize in Physics 1993". Nobel Foundation. Retrieved 2011-03-12. "for the discovery of a new type of pulsar, a discovery that has opened up new possibilities for the study of gravitation" 
  5. ^ a b Taylor, J. H.; Weisberg, J. M. (1982). "A new test of general relativity - Gravitational radiation and the binary pulsar PSR 1913+16". Astrophysical Journal 253: 908–920. Bibcode:1982ApJ...253..908T. doi:10.1086/159690. 
  6. ^ Taylor, J. H.; Weisberg, J. M. (1989). "Further experimental tests of relativistic gravity using the binary pulsar PSR 1913 + 16". Astrophysical Journal 345: 434–450. Bibcode:1989ApJ...345..434T. doi:10.1086/167917. 