Pulsar in the constellation Pictor
! style="text-align: center; background-color: #FFFFC0;" colspan="2" | Observation dataEpoch J2000      Equinox J2000
! style="text-align:left" | Constellation
! style="text-align:left" | Right ascension
! style="text-align:left" | Declination
! style="text-align:left" | Apparent magnitude (V)
! style="background-color: #FFFFC0; text-align: center;" colspan="2"| Characteristics
! style="text-align:left" | Spectral type
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PSR J0437−4715 is a pulsar. Discovered in the Parkes 70 cm survey, it remains the closest and brightest millisecond pulsar (MSP) known. The pulsar rotates about its axis 173.7 times per second and therefore completes a rotation every 5.75 milliseconds. It emits a searchlight-like radio beam that sweeps past the Earth each time it rotates. Currently the most precisely located object outside of the Solar System, PSR J0437-4715 is 156.3 parsecs or 509.8 light-years distant.
This pulsar is distinguished by being the most stable natural clock known and is debatably more stable than man-made atomic clocks. Its stability is about one part in 1015. Two other pulsars, PSR B1855+09 and PSR B1937+21 are known to be comparable in stability to atomic clocks, or about 3 parts in 1014.
PSR J0437−4715 is the first MSP to have its X-ray emission detected and studied in detail. It is also the first of only two pulsars to have the full three-dimensional orientation of its orbit determined.
Optical observations indicate that the binary companion of PSR J0437-4715 is most likely a low-mass helium white dwarf.
The pulsar is about 1.4 solar mass (M☉) and the companion is about 0.25 M☉. The pair revolve around each other every 5.75 days in nearly perfect circular orbits.
References.
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