Psr B1257 12

PSR B1257+12

Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Virgo
Right ascension 13h00m01s
Declination +12° 40' 57"
Spectral typeneutron star
Variable typePulsar
Massassumed 1.5 M
Radius~0.00002 R
Rotation0.006219 s
Age3 × 109 [1] years
Other designations
PSR J1300+1240 , PSR B1257+12 , PSR 1257+12 , PSR 1300+1240

PSR B1257+12 (PSR 1257+12), is a pulsar located 1000 light years from the Sun. In 2007, it was confirmed that three planets orbit the pulsar.


PSR B1257+12 is in the constellation of Virgo. The designation PSR B1257+12 refers to its coordinates in the B1950.0 epoch and it being a pulsar.

PSR B1257+12 was discovered by the Polish astronomer Aleksander Wolszczan in 1990 using the Arecibo radio telescope. It is a millisecond pulsar, a kind of neutron star, and was found to have anomalies in the pulsation period, which led to investigations as to the cause of the irregular pulses. In 1992 Wolszczan and Dale Frail published a famous paper on the first confirmed discovery of planets outside our solar system. Using refined methods one more planet was found orbiting this pulsar in 1994. The discovery stimulated a search for planets orbiting other pulsars, but it turned out such planets are rare; only one other pulsar planet, orbiting PSR B1620-26, has been confirmed. PSR B1257+12 has a rotation period of 6.22 milliseconds (9,650 rpm).

Planetary system



In 1992, Aleksander Wolszczan and Dale Frail discovered that the pulsar had two planets. These were the first discovery of extrasolar planets ever to be confirmed;[2][3] as pulsar planets, they surprised many astronomers who expected to find planets only around main-sequence stars. Additional uncertainty surrounded the system, because of a claim of an earlier pulsar planet around PSR 1829-10 that had to be retracted due to errors in calculations. Later, an additional planet was discovered. Additionally, this system may have an asteroid belt or a Kuiper belt.

The planets are believed to be the result of a second round of planetary system formation[4] resulting from unusual supernova remnants or a quark nova.[5]

The planets of PSR B1257+12 are designated from A to C (ordered by increasing distance), unlike planets around normal stars which follow the standard where the first discovered planet in the system is b, followed by c and so on.

Suspected fourth orbital body

In 1996, a possible Saturn-like (100 Earth mass) gas giant was announced orbiting the pulsar at a distance of about 40 AU.[6] The original hypothesis was retracted and a reinterpretation of the data led to a new hypothesis of a dwarf planet one-fifth the size of Pluto orbiting PSR B1257+12 at an average orbital distance of 2.4 AU with an orbital period of approximately 4.6 years.[7][8][9] The dwarf planet hypothesis was also retracted because further observations showed that the pulsation anomalies previously thought to reveal a fourth orbital body are "not periodic and can be fully explained in terms of slow changes in the pulsar’s dispersion measure."[9]

See also


External links

  • Pulsar Planets
  • The Extrasolar Planets Encyclopaedia

, +12° 40′ 57″

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