PSR B1257+12
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| Observation data Epoch J2000.0 Equinox J2000.0 |
|
|---|---|
| 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 1.4 M☉ |
| Radius | ~0.00002 R☉ |
| Luminosity | ? L☉ |
| Temperature | ? K |
| Metallicity | ? |
| Rotation | 0.006219 s |
| Age | 800 million years |
| Other designations | |
|
PSR J1300+1240
|
|
PSR B1257+12, sometimes abbreviated as PSR 1257+12, is a pulsar located 980 light-years from the Sun. As of 2007, it is confirmed that three extrasolar planets orbit the pulsar.
Contents |
[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 about 980 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. It has a rotation period of 6.22 milliseconds (9,646.3rpm).
[edit] Planetary system
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity |
|---|---|---|---|---|
| A | 0.025 M⊕ | 0.19 | 25.262 (± 0.003) | 0.00 |
| B | 4.3±0.2 M⊕ | 0.36 | 66.5419 (± 0.0001) | 0.0186 (± 0.0002) |
| C | 3.9±0.2 M⊕ | 0.46 | 98.2114 (± 0.0002) | 0.0252 (± 0.0002) |
| D (unconfirmed) | <0.0004 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 discovered [1]; as pulsar planets, they surprised many astronomers who expected to find planets only around main sequence stars. Additional uncertainty surrounded the system, because 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 either be the rocky cores of former gas giants (chthonian planets), or the result of a second round of planetary system formation resulting from unusual supernova remnants or a quark nova [2].
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 so small that it is not even considered to be a planet, but it is the first known extrasolar dwarf planet akin to the objects in the Kuiper belt in our solar system. It is possible that this object is the largest member of a belt of minor objects around the pulsar.
[edit] See also
[edit] References
- Wolszczan, A., Frail, D. (1992). "A planetary system around the millisecond pulsar PSR1257 + 12". Nature 355: 145–147. doi:. http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?1992Natur.355..145W&db_key=AST&nosetcookie=1.
- Wolszczan, A. (1994). "Confirmation of Earth Mass Planets Orbiting the Millisecond Pulsar PSR B1257+12". Science 264 (5158): 538–542. doi:. PMID 17732735. http://adsabs.harvard.edu/cgi-bin/bib_query?1994Sci...264..538W.
- Konacki, M., Wolszczan, A. (2003). "Masses and Orbital Inclinations of Planets in the PSR B1257+12 System". The Astrophysical Journal 591 (2): L147–L150. doi:. http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?2003ApJ...591L.147K&db_key=AST&nosetcookie=1.
- 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. doi:. http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?2000ApJ...528..907W&db_key=AST&nosetcookie=1.
- Salter, C. (2001). "Radio Astronomy Highlights" (PDF). Arecibo Newsletter (33). http://www.naic.edu/~newslet/no33/NAICNo33.pdf. Retrieved on 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.
- Pennsylvania State University (2005). Scientists announce smallest extra-solar planet yet discovered. Press release. 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 on 2008-06-06.
