PSR B1257+12 C

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PSR B1257+12 d
Extrasolar planet List of extrasolar planets
Exoplanet Comparison PSR B1257+12 C.png
Size comparison of PSR B1257+12 d 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) 0.46[1] AU
Eccentricity (e) 0.0252 ± 0.0002[1]
Orbital period (P) 98.2114 ± 0.0002[1] d
Inclination (i) 47 ± 3[1][note 1]°
Argument of
(ω) 108.3 ± 0.5[1]°
Time of periastron (T0) 2,449,766.5 ± 0.1[1] JD
Physical characteristics
Mass (m) 3.9 ± 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

PSR B1257+12 d (ex PSR B1257+12 C) is an extrasolar planet approximately 980 light-years away in the constellation of Virgo (the Virgin). PSR B1257+12C was one of the first planets ever discovered outside the Solar system, and is currently the third object known to be orbiting the pulsar PSR B1257+12. The planet is nearly four times as massive as the Earth.


Artist’s impression of PSR B1257+12 d.

The planets of PSR B1257+12 are designated from A to D (ordered by increasing distance). The reason that these planets are not named the same as the other extrasolar planets is mainly because of the time of their discovery. Being the first ever extrasolar planets discovered, and being discovered around a pulsar, the planets were given the uppercase letters "B" and "C" (like other planets). When a third planet was discovered around the system (in a closer orbit then the other two), the name "A" was commonly used. The name 51 Pegasi b (the first planet found around a Sun-like star) was the idea used for naming planets around regular stars.


  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 133 ± 3°.


External links[edit]

Media related to PSR B1257+12 C at Wikimedia Commons

Preceded by
Least massive exoplanet
1992 — 1994
Succeeded by
PSR B1257+12 A

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