PSR 1257+12 (also catalogued as PSR B1257+12,PSR 1300+1240 and PSR J1300+1240) is a pulsar located 2630 light years from Earth. It is believed to be orbited by at least four planets. These were the first extrasolar planets ever discovered. Composite Optical/X-ray image of the Crab Nebula pulsar, showing surrounding nebular gases stirred by the pulsars magnetic field and radiation. ... A light year, abbreviated ly, is the distance light travels in one year: roughly 9. ... Infrared Image of a possible extrasolar planet (lower left) in the Constellation Taurus, taken by the Hubble Space Telescope. ...

The pulsar

As seen from Earth, the pulsar is located in the sky at RA 13 00 01.00, DE +12 40.00 declination, as seen from Earth in the constellation of Virgo, using J2000 coordinates, hence the alternate names PSR 1300+1240 or PSR J1300+1240 (using B1950 coordinates, it would be located at RA 12 57 00, DE +12 00 declination, hence the alternate name PSR B1257+12) Right ascension (RA; symbol α: Greek letter alpha) is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. ... In astronomy declination (dec) is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. ... In astronomy declination (dec) is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. ... Earth, also known as the Earth or Terra, is the third planet outward from the Sun. ... Orion is a remarkable constellation, visible from most places on the globe (but not always the whole year long). ... This article is about the constellation and astrological sign Virgo. ... The J2000. ... The B1950. ...

PSR 1257+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 less than regular pulses. It has a mass of 0.29874213836478 M_SUN and a rotational period of 0.00621853193177 seconds, and is thought to be 800 million years old (as a neutron star). It is more characteristic of regular pulsars than other millisecond pulsars, and its sate is thought to be caused by core coalescence rather than mass accretion from a companion star (as there is no companion star).* Wikipedia does not yet have an article with this exact name. ... Aleksander Wolszczan (b. ... 1990 is a common year starting on Monday of the Gregorian calendar. ... Arecibo is a municipality in Puerto Rico named after the Taino Cacique Arasibo. ... A millisecond pulsar is a pulsar with a rotational period in the range of about 1-10 milliseconds. ... This article is about the celestial body. ...

The planets

In 1992, Wolszczan and Frail discovered that the pulsar has three planets and a possible comet. These were the first extrasolar planets ever discovered; 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. 1992 is a leap year starting on Wednesday of the Gregorian calendar. ... Infrared Image of a possible extrasolar planet (lower left) in the Constellation Taurus, taken by the Hubble Space Telescope. ... Pulsar planets are planets that are found orbiting pulsars. ... Hertzsprung-Russell diagram The main sequence of the Hertzsprung-Russell diagram is the curve where the majority of stars are located in this diagram. ... PSR 1829-10 is a pulsar located in the Scutum Constellation. ...

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. If they are the remains of planets orbiting the star before supernova, they were theoretically gas giants with large rocky cores, whose atmospheres were stripped away by the supernova, and which spiralled inward to their current orbits. Any planets in the orbits they currently occupy that were there before the supernova would have been destroyed.

• PSR 1257+12 A, the innermost planet, has a mass of 0.020 ± 0.002 M_E, with an average orbital distance of 0.19 AU, and an orbital period of 25.262 ± 0.003 days, on an orbital eccentricity of 0.0.=

• PSR 1257+12 B, the second planet, has a mass of 4.3 ± 0.2 M_E, with an average orbital distance of 0.36 AU, and an orbital period of 66.5419 ± 0.0001 days, on an orbital eccentricity of 0.0186 ± 0.0002.*

• PSR 1257+12 C, the third planet, has a mass of 3.9 ± 0.2 M_E, with an average orbital distance of 0.46 AU, and an orbital period of 98.2114 ± 0.0002 days, on an orbital eccentricity of 0.0252 ± 0.0002.*

• PSR 1257+12 D, the comet has an upper mass limit of 0.2 M_Pluto and an upper size of R < 1000km. *

*where AU is the average distance of the Earth from the Sun, M_E is the mass of the Earth, and M_SUN is the mass of the Sun (Sol)

See also

• Aleksander Wolszczan
• Pulsar planets
• Extrasolar planet
• Planetary system
• List of stars with confirmed extrasolar planets
• List of stars with multiple exoplanets
• Hypothetical planet

Aleksander Wolszczan (b. ... Pulsar planets are planets that are found orbiting pulsars. ... Infrared Image of a possible extrasolar planet (lower left) in the Constellation Taurus, taken by the Hubble Space Telescope. ... A planetary system consists of at least one star and various orbiting objects (such as asteroids, comets, moons, and planets). ... The following are lists of stars with confirmed extrasolar planets. ... The following are lists of stars with confirmed extrasolar planets. ... Hypothetical planets are planets that have been suggested as possibly existing (or have been believed to exist), but have never been proven to actually exist. ...

External links

• Earth Sized Planets Confirmed (http://www.space.com/scienceastronomy/aas_earthsize_020329.html)