PSR B1257+12 d
Extrasolar planet List of extrasolar planets
Size comparison of PSR B1257+12 d 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>0.46[1] AU</td></tr><tr> <td>Eccentricity</td> <td style="text-align: center">(e)</td> <td>0.0252 ± 0.0002[1]</td></tr><tr><td>Orbital period</td><td style="text-align: center">(P)</td> <td>98.2114 ± 0.0002[1] d</td></tr><tr> <td>Inclination</td> <td style="text-align: center">(i)</td> <td>47 ± 3[1][note 1]°</td></tr><tr> <td>Argument of
</td> <td style="text-align: center">(ω)</td> <td>108.3 ± 0.5[1]°</td></tr><tr> <td>Time of periastron</td> <td style="text-align: center">(T0)</td> <td>2,449,766.5 ± 0.1[1] JD</td></tr>

Physical characteristics

<tr><td>Mass</td><td style="text-align: center">(m)</td><td>3.9 ± 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 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.


File:PSR B1257+12 C.jpg

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°.

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:S-start Template:S-bef Template:S-ttl Template:S-aft Template:S-end

Template:PSR B1257+12

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

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