PSR 1257 plus 12 Guide, Meaning , Facts, Information and Description
PSR 1257+12 (PSR B1257+12,PSR 1300+1240,PSR J1300+1240) is a pulsar, located 2630 light years distant, at 13 00 01.00 right ascension, +12 40.00 declination, as seen from Earth, in the constellation Virgo, using J2000 coordinates, hence the alternate names PSR 1300+1240 or PSR J1300+1240. (Using B1950 coordinates, it would be 12 57 00 right ascension, +12 00 declination, hence the alternate name PSR B1257+12)
The pulsar was discovered by the polish astronomer Aleksander Wolszczan in 1990 using the Arecibo radio telescope. This millisecond pulsar was found to have anomalies in the pulsation period, which lead to investigations as to the cause of the less than regular pulses.
This system was discovered to have three planets, and a possible comet, by Aleksander Wolszczan and Frail in 1992. These were the first extrasolar planets ever discovered; as pulsar planets, they surprised many astronomers who expected planets around main sequence stars. Additional controversy surrounded the system, because a claim of an earlier pulsar planet around PSR 1829-10 had had to be retracted due to errors in calculations.
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 orbitting 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, the star, is a millisecond pulsar, a type of neutron star. It has a mass of 0.29874213836478 MSUN and a rotational period of 0.00621853193177 seconds, and is thought to be 800 million years old (as a neutron star). This millisecond pulsar is more characteristic of regular pulsars than other millisecond pulsars, and is thought to be caused by core coalescence rather than mass accretion from a companion star (as there is no companion star).*
PSR 1257+12 A, the innermost planet, has a mass of 0.020 ± 0.002 ME, 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 ME, 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 ME, 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, is estimated to have an average orbital distance of 35 AU, and an orbital period of 170 years.*
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