Lich (pulsar)
Pulsar Lich |
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Artist's impression of the planets orbiting PSR 1257 + 12 | |||||
Observation dates equinox : J2000.0 , epoch : J2000.0 |
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Constellation | Virgin | ||||
Right ascension | 13 h 00 m 3.11 s | ||||
declination | + 12 ° 40 ′ 55.2 ″ | ||||
Astrometry | |||||
Trigonometric parallax | (1.41 ± 0.08) | ||||
distance | (2310 ± 130) ly (710 ± 40) pc |
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Proper movement : | |||||
in right ascension | (46.5) mas / a | ||||
in declination | (−84.9) mas / a | ||||
Physical Properties | |||||
Rotation period | 6.219 ms | ||||
Age | 1 billion a | ||||
Dimensions | 1.4 M ☉ | ||||
history | |||||
discovery | 1992 | ||||
Other names and catalog entries |
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Aladin previewer |
Lich ( PSR B1257 + 12 or PSR J1300 + 1240 ) is a pulsar located in the constellation Virgo, 2300 light years from Earth. It is orbited by at least three planets. The exoplanets of this neutron star were the first planets to be discovered outside the solar system .
Origin of name
The pulsar was named by the IAU on December 15, 2015 after a publicly announced competition to name exoplanets and their central stars. The name Lich was suggested by the Planetarium Südtirol and uses the term Lich for a fictional undead figure. The name refers to the fact that this pulsar is a dead, but still active star core. Lich's planets also have names for ghosts, zombies, or undead creatures.
Pulsar data
The pulsar Lich was discovered in 1990 by the Polish astronomer Aleksander Wolszczan and was only called "PSR B1257 + 12" at that time. The period of rotation of the pulsar is 6.219 milliseconds , its mass is given as 1.4 solar masses and it is located about 710 parsecs (2300 light years ) from Earth.
Discovery of orbital objects
The pulses of the neutron star arrived with regular delays, which the scientists Wolszczan and Frail pointed out that it is accompanied by two satellites, which cause these variations. All in all, four satellites - Draugr , Poltergeist , Phobetor and PSR 1257 + 12 e - were then discovered, the last of which (PSR 1257 + 12 e) is considered a comet .
The comet PSR 1257 + 12 e has a maximum of 0.2 times the mass of Pluto and a maximum diameter of 1,000 kilometers.
Since neutron stars are the result of a supernova , it was unclear how such an event could create planets in the orbit of the pulsar. The question arises whether they existed there before the supernova (and if so, how did they survive it?), Or whether they emerged from the wreckage of the star explosion, or whether they were "captured" by the pulsar. The radii of the planets are not known and can only be estimated based on their mass.
Planet (order from the star) |
Discovered |
Mass ( earth masses ) |
Major semiaxis of the orbit ( AE ) |
Rotation time ( days ) |
eccentricity |
Orbit inclination ( degree ) |
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Draugr | 1992 | 0.022 | 0.19 | 25.262 | 0 | - |
poltergeist | 1992 | 4.13 | 0.36 | 66.5419 | 0.0186 | 53 |
Phobetor | 1992 | 3.82 | 0.46 | 98.2114 | 0.0252 | 47 |
See also
- Helvetios , originally 51 Pegasi. The first sun-like star around which the exoplanet Dimidium (51 Pegasi b) could be detected in 1995 .
Individual evidence
- ↑ a b Simbad
- ↑ a b Exoplanet.eu
- ↑ International Astronomical Union: NameExoWorlds - The Approved Names. Retrieved April 11, 2016 .
- ↑ Very long baseline interferometry astrometry of PSR B1257 + 12, a pulsar with a planetary system , accessed December 21, 2015