PSR B1257+12
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| Observation data Epoch J2000.0 Equinox J2000.0 |
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| Constellation | Virgo |
| Right ascension | 13h00m01s |
| Declination | +12° 40' 57" |
| Apparent magnitude (V) | ? |
| Characteristics | |
| Spectral type | neutron star |
| U−B color index | ? |
| B−V color index | ? |
| Variable type | Pulsar |
| Details | |
| Mass | assumed 1.5 M☉ |
| Radius | ~0.00002 R☉ |
| Luminosity | ? L☉ |
| Temperature | ? K |
| Metallicity | ? |
| Rotation | 0.006219 s |
| Age | 3 × 109 [1] years |
| Other designations | |
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PSR J1300+1240
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PSR B1257+12, sometimes abbreviated as PSR 1257+12, is a pulsar located roughly 2000 light-years from the Sun. In 2007, it was confirmed that three extrasolar planets orbit the pulsar.
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[edit] Pulsar
PSR B1257+12 is in the constellation of Virgo. The designation PSR B1257+12 refers to its coordinates in the B1950.0 epoch. It is located roughly 2000 light years from Earth.
PSR B1257+12 was discovered by the Polish astronomer Aleksander Wolszczan in 1990 using the Arecibo radio telescope. It is a millisecond pulsar, a kind of neutron star, and was found to have anomalies in the pulsation period, which led to investigations as to the cause of the irregular pulses. In 1992 Wolszczan and Dale Frail published a famous paper on the first confirmed discovery of planets outside our solar system. Using refined methods one more planet was found orbiting this pulsar in 1994, and a fourth was found in 2002. The discovery started a search for planets orbiting other pulsars, but it turned out such as rare, only one other planet have been confirmed orbiting PSR B1620-26. PSR B1257+12 has a rotation period of 6.22 milliseconds (9,650 rpm).
[edit] Planetary system
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity |
|---|---|---|---|---|
| A (b) | 0.020 ± 0.002 M⊕ | 0.19 | 25.262 ± 0.003 | 0.0 |
| B (c) | 4.3 ± 0.2 M⊕ | 0.36 | 66.5419 ± 0.0001 | 0.0186 ± 0.0002 |
| C (d) | 3.9 ± 0.2 M⊕ | 0.46 | 98.2114 ± 0.0002 | 0.0252 ± 0.0002 |
| D (e) |
0.0004[2] M⊕ | 2.6 | 1250 | ? |
[edit] Planets
In 1992, Aleksander Wolszczan and Dale Frail discovered that the pulsar has two planets. These were the first extrasolar planets ever to be confirmed;[3][4] as pulsar planets, they surprised many astronomers who expected to find planets only around main-sequence stars. Additional uncertainty surrounded the system, because of a claim of an earlier pulsar planet around PSR 1829-10 that had to be retracted due to errors in calculations. Later, an additional planet was discovered. Additionally, this system may have an asteroid belt or a Kuiper belt.
The planets are believed to be the result of a second round of planetary system formation[5] resulting from unusual supernova remnants or a quark nova.[6]
The planets of PSR B1257+12 are designated from A to D (ordered by increasing distance), unlike planets around normal stars which follow the standard where the first discovered planet in the system is b, followed by c and so on.
[edit] Suspected fourth orbital body (dwarf planet)
In 1996, a possible Saturn-like (100 Earth mass) gas giant was announced orbiting the pulsar at a distance of about 40 AU. However, the discovery was not conclusive and was later retracted. It is now thought that the signal came from a dwarf-planetary body.
It is suspected that a dwarf planet is orbiting PSR B1257+12 at an average orbital distance of 2.6 AU with an orbital period of approximately 3.5 years. The object is thought to be very small, less than 20% of the mass of Pluto.[2]
[edit] See also
[edit] References
- ^ a b 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.
- ^ a b PSR 1257+12 d
- ^ "Pulsar Planets". http://www.astro.psu.edu/users/alex/pulsar_planets.htm.
- ^ 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.
- ^ Podsiadlowski, P. (1993). "Planet Formation Scenarios". Planets around pulsars; Proceedings of the Conference, California Inst. of Technology, Pasadena, Apr. 30-May 1, 1992: 149–165. Bibcode 1993ASPC...36..149P. http://adsabs.harvard.edu/abs/1993ASPC...36..149P.
- ^ Planets orbiting Quark Nova compact remnants. arXiv:astro-ph/0301574. Bibcode 2003A&A...407L..51K. doi:10.1051/0004-6361:20030957.
- Wolszczan, A. (1994). "Confirmation of Earth Mass Planets Orbiting the Millisecond Pulsar PSR B1257+12" (pdf). Science 264 (5158): 538–542. Bibcode 1994Sci...264..538W. doi:10.1126/science.264.5158.538. PMID 17732735. http://www.astro.psu.edu/~niel/astro550/week07-wolszczan-pulsar-planets.pdf.
- Wolszczan, A. et al. (2000). "Timing Observations of Four Millisecond Pulsars with the Arecibo and Effelsberg Radio Telescopes". The Astrophysical Journal 528 (2): 907–912. Bibcode 2000ApJ...528..907W. doi:10.1086/308206.
- Salter, C. (2001). "Radio Astronomy Highlights" (PDF). Arecibo Newsletter (33). http://www.naic.edu/~newslet/no33/NAICNo33.pdf. Retrieved 2009-06-23.
- Daniel Fischer (2002). "A comet orbiting a pulsar?". The Cosmic Mirror (244). http://www.astro.uni-bonn.de/~dfischer/mirror/244.html.
- "Scientists announce smallest extra-solar planet yet discovered" (Press release). Pennsylvania State University. 2005. http://live.psu.edu/story/10180.
[edit] External links
- Pulsar Planets
- PSR 1257+12 on The Extrasolar Planets Encyclopaedia
- Britt, Robert Roy (29 May 2003). "A World With Two Suns". SPACE.com. http://www.space.com/scienceastronomy/aas_earthsize_020329.html. Retrieved 2008-06-06.
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