PSR B1257+12 c
Extrasolar planet List of extrasolar planets
Size comparison of PSR B1257+12 B with Earth and Neptune.
(Based on selected hypothetical modeled compositions)
Parent star

<tr> <td colspan="2">Star</td> <td>PSR B1257+12</td></tr><tr> <td colspan="2">Constellation</td> <td>Virgo</td></tr><tr> <td>Right ascension</td> <td style="text-align: center">(α)</td> <td>13h 00m 01s</td></tr><tr> <td>Declination</td> <td style="text-align: center">(δ)</td> <td>+12° 40′ 57″</td></tr><tr><td colspan="2">Distance</td><td>980 ly
(300 pc)</td></tr><tr><td colspan="2">Spectral type</td> <td>Pulsar</td></tr><tr> <td>Mass</td> <td style="text-align: center">(m)</td> <td>assumed 1.4 M</td></tr><tr> <td>Radius</td> <td style="text-align: center">(r)</td> <td>~0.00002 R</td></tr><tr> <td>Age</td> <td style="text-align: center"></td> <td>0.8 Gyr</td></tr>

Orbital elements

<tr><td>Semimajor axis</td><td style="text-align: center">(a)</td> <td>0.36[1] AU</td></tr><tr> <td>Eccentricity</td> <td style="text-align: center">(e)</td> <td>0.0186 ± 0.0002[1]</td></tr><tr><td>Orbital period</td><td style="text-align: center">(P)</td> <td>66.5419 ± 0.0001[1] d</td></tr><tr> <td>Inclination</td> <td style="text-align: center">(i)</td> <td>53 ± 4[1][note 1]°</td></tr><tr> <td>Argument of
</td> <td style="text-align: center">(ω)</td> <td>250.4 ± 0.6[1]°</td></tr><tr> <td>Time of periastron</td> <td style="text-align: center">(T0)</td> <td>2,449,768.1 ± 0.1[1] JD</td></tr>

Physical characteristics

<tr><td>Mass</td><td style="text-align: center">(m)</td><td>4.3 ± 0.2[1] M</td></tr>

Discovery information

<tr> <td colspan="2">Discovery date</td> <td>22 January 1992</td></tr><tr> <td colspan="2">Discoverer(s)</td> <td>Aleksander Wolszczan</td></tr><tr> <td colspan="2">Discovery method</td> <td>Pulsar Timing</td></tr><tr> <td colspan="2">Discovery site</td> <td>Template:Country data Poland</td></tr><tr> <td colspan="2">Discovery status</td> <td>Published</td></tr> <tr style="background-color: #A0B0FF;"><td align=center colspan=3>Database references</td></tr><tr valign=baseline><td colspan=2>Extrasolar Planets
</td><td>data</td></tr><tr><td colspan=2>SIMBAD</td><td>data</td></tr>

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.


File:PSR B1257+12 B.jpg

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°.

References Edit

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Konacki, M., Wolszczan, A. (2003). Masses and Orbital Inclinations of Planets in the PSR B1257+12 System. The Astrophysical Journal 591 (2): L147–L150.
  • Wolszczan, A., Frail, D. (1992). A planetary system around the millisecond pulsar PSR1257 + 12. Nature 355 (6356): 145–147.

External linksEdit


Template:PSR B1257+12

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

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