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| Observation data Epoch J2000.0 Equinox J2000.0 |
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| Constellation | Virgo |
| Right ascension | 13h00m01s |
| Declination | +12° 40' 57" |
| Apparent magnitude (V) | ? |
| Characteristics | |
| Spectral type | neutron star |
| U−B color index | ? |
| B−V color index | ? |
| Variable type | Pulsar |
| Details | |
| Mass | assumed 1.5 M☉ |
| Radius | ~0.00002 R☉ |
| Luminosity | ? L☉ |
| Temperature | ? K |
| Metallicity | ? |
| Rotation | 0.006219 s |
| Age | 3 × 109 [1] years |
| Other designations | |
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PSR J1300+1240
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PSR B1257+12, sometimes abbreviated as PSR 1257+12, is a pulsar located roughly 2000 light-years from the Sun. In 2007, it was confirmed that three extrasolar planets orbit the pulsar.
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PSR B1257+12 is in the constellation of Virgo. The designation PSR B1257+12 refers to its coordinates in the B1950.0 epoch. It is located roughly 2000 light years from Earth.
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. It has a rotation period of 6.22 milliseconds (9,650 rpm).
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity |
|---|---|---|---|---|
| A (b) | 0.020 ± 0.002 M⊕ | 0.19 | 25.262 ± 0.003 | 0.0 |
| B (c) | 4.3 ± 0.2 M⊕ | 0.36 | 66.5419 ± 0.0001 | 0.0186 ± 0.0002 |
| C (d) | 3.9 ± 0.2 M⊕ | 0.46 | 98.2114 ± 0.0002 | 0.0252 ± 0.0002 |
| D (e) |
0.0004[2] M⊕ | 2.6 | 1250 | ? |
In 1992, Aleksander Wolszczan and Dale Frail discovered that the pulsar has two planets. These were the first extrasolar planets ever to be confirmed;[3][4] 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[5] resulting from unusual supernova remnants or a quark nova.[6]
The planets of PSR B1257+12 are designated from A to D (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.
In 1996, a possible Saturn-like (100 Earth mass) gas giant was announced orbiting the pulsar at a distance of about 40 AU. However, the discovery was not conclusive and was later retracted. It is now thought that the signal came from a dwarf-planetary body.
It is suspected that a dwarf planet is orbiting PSR B1257+12 at an average orbital distance of 2.6 AU with an orbital period of approximately 3.5 years. The object is thought to be very small, less than 20% of the mass of Pluto.[2]
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