Lich (pulsar)

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Pulsar
Lich
Artist's impression of the planets orbiting PSR 1257 + 12
Artist's impression of the planets orbiting PSR 1257 + 12
Observation
dates equinox :  J2000.0 , epoch : J2000.0
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
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
Catalog of pulsars
PSR J1300 + 1240
PSR B1257 + 12
Swell:
  1. ^ Catalog of Pulsars
  2. ^ Catalog of Pulsars
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.

Lich planets
Planet
(order
from the star) 		Discovered Mass
( earth masses ) 		Major semiaxis of
the orbit
( AE ) 		Rotation time
( days ) 		eccentricity Orbit inclination
( degree )
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
A simulated representation of the Lich planetary system

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

  1. ↑ a b Simbad
  2. ↑ a b Exoplanet.eu
  3. ↑ International Astronomical Union: NameExoWorlds - The Approved Names. Retrieved April 11, 2016 .
  4. ↑ Very long baseline interferometry astrometry of PSR B1257 + 12, a pulsar with a planetary system , accessed December 21, 2015