Geminga

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Pulsar
Geminga
Geminga's position in the Milky Way (NASA / DOE / International LAT Team)
Geminga's position in the Milky Way (NASA / DOE / International LAT Team)
Observation
dates equinox :  J2000.0 , epoch : J2000.0
Constellation Twins
Right ascension 06 h 33 m 54.15 s
declination + 17 ° 46 ′ 12.9 ″
Astrometry
Trigonometric parallax (4.0 ± 1.3) mas
distance  815 ly 250 pc 
 
Dispersion measure (2.9 ± 0.5) pc cm −3
Proper movement : 
in right ascension 142.2 ± 1.2  mas / a
in declination 107.4 ± 1.2  mas / a
Physical Properties
brightness

V-band: approx. 25.5 mag
2.3 ∙ 10 −30 erg cm −2 s −1 Hz −1

Rotation period 237 ms
Age 300,000  a
history
discovery as a source of gamma radiation: Fichtel et al. with SAS-2 , 1972
confirmation as pulsar: 1992
Other names
and catalog entries
Catalog of pulsars
PSR J0633 + 1746
PSR J0633 + 17
PSR B0633 + 17
PSR B0630 + 17
PSR B0630 + 18
Second EGRET Gamma-ray catalog
2EG J0633 + 1745
Third EGRET Gamma-ray catalog
3EG J0633 + 1751
Extreme Ultra-Violet Explorer Catalog
EUVE J0633 + 17.7
ROSAT All-Sky Bright Source Catalog
1RXS J063354.1 + 174612
Swell:
  1. ^ Catalog of Pulsars
  2. ^ Catalog of Pulsars
  3. ^ Catalog of Pulsars
  4. ^ Catalog of Pulsars
  5. ^ Catalog of Pulsars
  6. ↑ 2nd EGRET catalog
  7. ↑ > 3rd EGRET catalog
  8. ↑ Extreme Ultra-Violet Explorer Catalogs
  9. ↑ ROSAT catalog
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Geminga is a pulsar in the constellation Gemini ( Latin Gemini ). The distance is about 800  light years , but it is fraught with great inaccuracy. Geminga and the Vela pulsar , about the same distance away, are the closest known pulsars to the earth.

The name is derived from GEMINi GAmma ray source (Gemini gamma ray source ). Geminga was discovered in 1972 with the help of the SAS-2 satellite and is the second brightest known source of gamma radiation of over 100 MeV energy (the brightest is the Vela pulsar and the third brightest is the pulsar in the Crab Nebula ). In 1992 the X-ray satellite ROSAT was able to demonstrate a periodicity of the radiation of 0.237 seconds, making Geminga a pulsar. In contrast to other known pulsars, Geminga only emits weakly in the radio range .

Geminga was created around 300,000 years ago in a supernova explosion . According to some theories, this explosion is the cause of the relatively low density of interstellar matter in the vicinity of the solar system . This phenomenon is called the local bubble .

Measurements of variations in the period of Geminga's gamma pulses in 1998 suggested the possible existence of a companion in orbit around Geminga. Later observations suggested timing noise as the more likely explanation and the planetary hypothesis is no longer pursued today.

Web links

Individual evidence

  1. ↑ SIMBAD database
  2. ↑ a b c Faherty J. Walter FM, Anderson J .: The trigonometric parallax of the neutron star Geminga . In: Astrophys. Space Sci. tape 308 , 2007, p. 225-230 , doi : 10.1007 / s10509-007-9368-0 .
  3. ↑ Bignami GF , PA Caraveo: Geminga: Its Phenomenology, Its Fraternity, and Its Physics . In: Annu. Rev. Astron. Astrophys. tape 34 , 1996, pp. 331 , doi : 10.1146 / annurev.astro.34.1.331 .
  4. ↑ VM Malofeev and OI Malov: Detection of Geminga as a radio pulsar . In: Nature . tape 389 , October 16, 1997, p. 697-699 , doi : 10.1038 / 39530 (English).
  5. ^ Gehrels N., Chen W .: The Geminga supernova as a possible cause of the local interstellar bubble . In: Nature . tape 361 , 1993, pp. 706-707 , doi : 10.1038 / 361706a0 .
  6. ^ JR Mattox, JP Halpern, and PA Caraveo: Timing the Geminga pulsar with gamma-ray observations . In: Astrophys. J. Band 493 . The American Astronomical Society, Feb. 1, 1998, p. 891–897 , doi : 10.1086 / 305144 / meta (English, iop.org [accessed February 2, 2017]).
  7. ^ JR Mattox, JP Halpern, PA Caraveo: An Update on Timing the Geminga Pulsar with the EGRET Gamma-Ray Telescope . In: Bulletin of the American Astronomical Society . tape 31 , 1999, p. 904 ( aas.org ).
  8. ↑ MS Jackson, JP Halpern, EV Gotthelf and JR Mattox: A High-Energy Study of the Geminga Pulsar . In: Astrophys. J. Band 578 , no. 2 , p. 935 , doi : 10.1086 / 342662 .