PSR B1257+12 B
| Extrasolar planet | List of extrasolar planets | |
|---|---|---|
 (Based on selected hypothetical modeled compositions) |
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| Parent star | ||
| Star | PSR B1257+12 | |
| Constellation | Virgo | |
| Right ascension | (α) | 13h 00m 01s |
| Declination | (δ) | +12° 40′ 57″ |
| Distance | 980 ly (300 pc) |
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| 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 periastron |
(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 | |
| Detection method | Pulsar Timing | |
| Discovery site |  Poland |
|
| Discovery status | Published | |
| Database references | ||
| Extrasolar Planets Encyclopaedia |
data | |
| SIMBAD | data | |
PSR B1257+12B 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 the second object 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.
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[edit] Name
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 planets 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.
[edit] Notes
- ^ 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°.
[edit] References
- ^ a b c d e f g Konacki, M., Wolszczan, A. (2003). "Masses and Orbital Inclinations of Planets in the PSR B1257+12 System". The Astrophysical Journal 591 (2): L147–L150. arXiv:astro-ph/0305536. Bibcode 2003ApJ...591L.147K. doi:10.1086/377093. http://www.iop.org/EJ/article/1538-4357/591/2/L147/17269.html.
- Wolszczan, A., Frail, D. (1992). "A planetary system around the millisecond pulsar PSR1257 + 12". Nature 355 (6356): 145–147. Bibcode 1992Natur.355..145W. doi:10.1038/355145a0.
[edit] External links
Media related to PSR B1257+12 B at Wikimedia Commons
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Coordinates: 
13h 00m 01s, +12° 40′ 57″
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