PSR B1257+12 C
PSR B1257+12 C, alternatively designated PSR B1257+12 d, also named Phobetor, is an extrasolar planet approximately 980 light-years away in the constellation of Virgo. PSR B1257+12 C was one of the first planets ever discovered outside the Solar system, and is currently the third object known to be orbiting the pulsar PSR B1257+12, i.e. a pulsar planet in the dead stellar system. The planet is nearly four times as massive as the Earth.
Nomenclature
The convention that arose for designating pulsars was that of using the letters PSR (Pulsating Source of Radio) followed by the pulsar's right ascension and degrees of declination. The modern convention prefixes the older numbers with a B meaning the coordinates are for the 1950.0 epoch. All new pulsars have a J indicating 2000.0 coordinates and also have declination including minutes. Pulsars that were discovered before 1993 tend to retain their B names rather than use their J names, but all pulsars have a J name that provides more precise coordinates of its location in the sky.
PSR B1257+12 B
PSR B1257+12 B, alternatively designated PSR B1257+12 c, also named Poltergeist, is an extrasolar planet approximately 980 light-years away in the constellation of Virgo. It was the first planet ever discovered outside the Solar System, and is one of three pulsar planets known to be orbiting the pulsar PSR B1257+12.
Over four times as massive as the Earth, it circles the primary at a distance of 0.36 AU with an orbital period of approximately 66 days. Because it and PSR B1257+12 C have very similar masses and orbit close to each other, they were expected to cause measurable perturbations in each other's orbits. Detecting such perturbations confirmed that the planets were real. Accurate masses of the two planets, as well as their inclinations, were calculated from how much the planets perturb each other.
Nomenclature
The convention that arose for designating pulsars was that of using the letters PSR (Pulsating Source of Radio) followed by the pulsar's right ascension and degrees of declination. The modern convention prefixes the older numbers with a B meaning the coordinates are for the 1950.0 epoch. All new pulsars have a J indicating 2000.0 coordinates and also have declination including minutes. Pulsars that were discovered before 1993 tend to retain their B names rather than use their J names, but all pulsars have a J name that provides more precise coordinates of its location in the sky.
PSR B1257+12
PSR B1257+12, previously designated PSR 1257+12, alternatively designated PSR J1300+1240, also named Lich, is a pulsar located 2300 light years from the Sun in the constellation of Virgo.
The pulsar has a planetary system with three known extrasolar planets (designated PSR B1257+12 A, B and C; later named Draugr, Poltergeist and Phobetor, respectively). They were both the first extrasolar planets and the first pulsar planets to be discovered; A and B in 1992 and C in 1994. A is the lowest mass planet yet discovered by any observational technique, with somewhat less than twice the mass of Earth's moon.
Nomenclature
The convention that arose for designating pulsars was that of using the letters PSR (Pulsating Source of Radio) followed by the pulsar's right ascension and degrees of declination. The modern convention prefixes the older numbers with a B meaning the coordinates are for the 1950.0 epoch. All new pulsars have a J indicating 2000.0 coordinates and also have declination including minutes. Pulsars that were discovered before 1993 tend to retain their B names rather than use their J names, but all pulsars have a J name that provides more precise coordinates of its location in the sky.
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