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Some 2,300 light years from the Sun in the constellation of Virgo lies the pulsar named PSR B1257+12, or Lich. An object only about 20km in diameter, the pulsar nonetheless generates more than five times the Sun's energy, and exerts an intense gravitational field. In close orbits around Lich are three planets named Draugr, Poltergeist and Phobetor; the latter two, Poltergeist and Phobetor, are historically important as, in 1992, they were the first extrasolar planets to be discovered.

Phobetor is the outermost of the three known planets of Lich, but all three pursue extremely close orbits around the pulsar. Phobetor's orbital distance is 0.46 AU, less than half the distance from the Sun to Earth, and it completes this orbit in less than one hundred days. Physically the planet is of the type known as a 'super Earth'; Phobetor appears to be a solid body, but has 1.5 times the Earth's diameter, and nearly four times its mass.

The Lich pulsar and its planets are not directly visible, but this image shows its location in the sky, northward of the third-magnitude star Vindemiatrix in Virgo. Imagery provided by Aladin sky atlas

Because Phobetor was one of the first confirmed extrasolar planets to be discovered, it was designated before formal naming rules had been established, and so it was initially classified as 'PSR B1257+12 C', where 'C' indicated that it was the third planet of the pulsar. By the now standard method of designation, Phobetor is instead catalogued as 'PSR B1257+12 d'. It gained the name Phobetor (referring a mythical creature said to appear in beastly form during nightmares) in 2015, as part of public vote on naming certain important extrasolar planets.


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