PSR B1257+12 B

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PSR B1257+12 c
Extrasolar planet List of extrasolar planets
Exoplanet Comparison PSR B1257+12 B.png
Size comparison of PSR B1257+12 B with Earth and Neptune.
(Based on selected hypothetical modeled compositions)
Parent star
Star PSR B1257+12
Constellation Virgo
Right ascension (α) 13h 00m 01s
Declination (δ) +12° 40′ 57″
Distance 980 ly
(300 pc)
Spectral type Pulsar
Mass (m) assumed 1.4 M
Radius (r) ~0.00002 R
Age 0.8 Gyr
Orbital elements
Semimajor axis (a) 0.36[1] AU
Eccentricity (e) 0.0186 ± 0.0002[1]
Orbital period (P) 66.5419 ± 0.0001[1] d
Inclination (i) 53 ± 4[1][note 1]°
Argument of
(ω) 250.4 ± 0.6[1]°
Time of periastron (T0) 2,449,768.1 ± 0.1[1] JD
Physical characteristics
Mass (m) 4.3 ± 0.2[1] M
Discovery information
Discovery date 22 January 1992
Discoverer(s) Aleksander Wolszczan
Discovery method Pulsar Timing
Discovery site  Poland
Discovery status Published
Database references
Extrasolar Planets
Exoplanet Archive data
Open Exoplanet Catalogue data

PSR B1257+12 c (ex PSR B1257+12 B) is an extrasolar planet (approximately 980 light-years away) in the constellation of Virgo (the Virgin). PSR B1257+12B was the first planet ever discovered outside the Solar System, and is one of three objects known to be orbiting the pulsar PSR B1257+12, which it circles at a distance of 0.36 AU with an orbital period of approximately 66 days. The planet is over four times as massive as the Earth. Because planet B and planet C have very similar masses (as well as orbiting close to each other), they cause measurable perturbations in each other's orbits. As expected, perturbations were detected confirming that the planets were real. Accurate masses of the two planets, as well as their inclinations, were measured by calculating how much the planets interfere with each other.


PSR B1257+12 c in Celestia.

The planets of PSR B1257+12 are designated from A to D (ordered by increasing distance). The reason that these planets have different naming conventions from other extrasolar planets is because the naming conventions differed at the time of their discovery. Being the first ever exoplanets discovered, and being discovered around a pulsar, the planets were given the uppercase letters "B" and "C." When a third planet was later discovered around the system (in a closer orbit than the other two), the name "A" was used.


  1. ^ The method used to determine the inclination includes a degeneracy because of the impossibility of determining whether the orbital motion is clockwise or anticlockwise. The alternate value of the inclination is 127 ± 4°.


External links[edit]

Media related to PSR B1257+12 B at Wikimedia Commons

Coordinates: Sky map 13h 00m 01s, +12° 40′ 57″