PSR J0437−4715 is a

pulsar A pulsar (''pulsating star, on the model of quasar'') is a highly magnetized rotating neutron star that emits beams of electromagnetic radiation out of its Poles of astronomical bodies#Magnetic poles, magnetic poles. This radiation can be obse ...

. Discovered in the Parkes 70 cm survey, it remains the closest and brightest

millisecond pulsar A millisecond pulsar (MSP) is a pulsar with a rotational period less than about 10 milliseconds. Millisecond pulsars have been detected in radio pulsar, radio, X-ray pulsar, X-ray, and gamma ray portions of the electromagnetic spectrum. The leadi ...

(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. Until the

Gaia mission ''Gaia'' was a space observatory of the European Space Agency (ESA) that was launched in 2013 and operated until March 2025. The spacecraft was designed for astrometry: measuring the positions, distances and motions of stars with unprecedented ...

, it was the most precisely located object outside of the

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...

, recorded in 2008 at

parsecs The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to or (AU), i.e. . The parsec unit is obtained by the use of parallax and trigonometry, and ...

light-years A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astro ...

distant. This pulsar is distinguished by being the most stable natural clock known and is debatably more stable than man-made

atomic clocks An atomic clock is a clock that measures time by monitoring the resonant frequency of atoms. It is based on atoms having different energy levels. Electron states in an atom are associated with different energy levels, and in transitions betwee ...

. Its stability is about one part in 10¹⁵. Two other pulsars, PSR B1855+09 and

PSR B1937+21 PSR may refer to: Organizations * Pacific School of Religion, Berkeley, California, US * Palestinian Center for Policy and Survey Research * Payment Systems Regulator in the United Kingdom * Physicians for Social Responsibility, US Political par ...

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 A white dwarf is a Compact star, stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very density, dense: in an Earth sized volume, it packs a mass that is comparable to the Sun. No nuclear fusion takes place i ...

. The pulsar is about 1.4

solar mass The solar mass () is a frequently used unit of mass in astronomy, equal to approximately . It is approximately equal to the mass of the Sun. It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxie ...

() and the companion is about 0.25 . The pair revolve around each other every 5.75 days in nearly perfect circular orbits.

References

{{DEFAULTSORT:PSR J0437-4715 Pictor Millisecond pulsars Binary stars

See also

References