Pulsar
PSR B1257+12 is in the constellation of Virgo. The designation PSR B1257+12 refers to its coordinates in the B1950.0 epoch.
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 are 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).
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