PSR B1257+12

Starbox begin
name = PSR B1257+12 Starbox observe
epoch = J2000.0
constell = Virgo
ra = 13^h00^m01^s
dec = +12° 40' 57"
appmag_v = ?Starbox character
class = ?
b-v = ?
u-b = ?
variable = Pulsar Starbox detail
mass = assumed 1.4
radius = ~0.00002
luminosity = ?
temperature = ?
metal = ?
rotation = 0.006219 s
age = 800 million Starbox catalog
names = 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.

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).

Planetary system

PlanetboxOrbit
exoplanet = A
mass_earth = 0.025
period = 25.262 (± 0.003)
semimajor = 0.19
eccentricity = 0.00OrbitboxPlanet
exoplanet = B
mass_earth = 4.3±0.2
period = 66.5419 (± 0.0001)
semimajor = 0.36
eccentricity = 0.0186 (± 0.0002)OrbitboxPlanet
exoplanet = C
mass_earth = 3.9±0.2
period = 98.2114 (± 0.0002)
semimajor = 0.46
eccentricity = 0.0252 (± 0.0002)OrbitboxPlanet hypothetical
exoplanet = D
mass_earth = <0.0004
period = 1250
semimajor = 2.6

Planets

In 1992, Aleksander Wolszczan and Dale Frail discovered that the pulsar has two planets. These were the first extrasolar planets ever discovered [cite web |url=http://www.astro.psu.edu/users/alex/pulsar_planets.htm |title=Pulsar Planets] ; 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, or the result of a second round of planetary system formation resulting from unusual supernova remnants.

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.

Suspected fourth orbital body (comet)

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 an asteroidal or cometary body.

It is suspected that an asteroid or comet 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 asteroid or comet 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.

See also

* 51 Pegasi
* PSR B1620-26

References

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External links

* [http://www.astro.psu.edu/users/alex/pulsar_planets.htm Pulsar Planets]
* [http://exoplanet.eu/star.php?st=PSR+1257%2B12 PSR 1257+12] on " [http://exoplanet.eu/index.php The Extrasolar Planets Encyclopaedia] "
*cite news
first=Robert Roy
last=Britt
title= A World With Two Suns
url=http://www.space.com/scienceastronomy/aas_earthsize_020329.html
publisher="SPACE.com"
date=29 May 2003
accessdate=2008-06-06