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NGC 246

NGC 246
Emission nebula
Planetary nebula
An infrared Spitzer Space Telescope image of NGC 246.
Credit: NASA/JPL.
Observation data: J2000 epoch
Right ascension00h 47m 03.338s[1]
Declination−11° 52′ 18.94″[1]
Distance1,600 ly
Apparent magnitude (V)8[2] / 11.8 (central star)[1]
Apparent dimensions (V)3.8′[2]
ConstellationCetus
Physical characteristics
Radius2-3[3] ly
DesignationsSkull Nebula,[4] Pac-Man Nebula,[5] Caldwell 56, HIP 3678, PMN J0047-1152, 2E 178, PN VV 4, IRAS 00445-1207, MCT 0044-1208[1]
See also: Lists of nebulae

NGC 246 (also known as the Skull Nebula[4] or Caldwell 56) is a planetary nebula in the constellation Cetus. It is the first known planetary nebula to have a hierarchical triple star system at its center.[6] The nebula and the stars associated with it are listed in several catalogs, as summarized by the SIMBAD database.[1] NGC 246 was discovered by William Herschel in 1785.

The nebula is roughly 1,600 light-years away.[7] NGC 246's central star is the 12th magnitude[7] white dwarf HIP 3678 A.[8]

NGC 246 is not to be confused with the Rosette Nebula (NGC 2337), which is also referred to as the "Skull."[9] Among some amateur astronomers, NGC 246 is known as the "Pac-Man Nebula" because of the arrangement of its central stars and the surrounding star field.[5]

Discovery and research

In 1785, William Herschel discovered NGC 246.

In 2014, astronomers discovered a second companion to NGC 246's central star, HIP 3678 A, which has a comoving companion star called HIP 3678 B.[6] The second companion star, a red dwarf known as HIP 3678 C, was discovered using the European Southern Observatory's Very Large Telescope.[6]

  • HaRGB image of The Skull Nebula (NGC 246). Data from the Liverpool Telescope, processed by Göran Nilsson. Total exposure time 1.1 hours.
    HaRGB image of The Skull Nebula (NGC 246). Data from the Liverpool Telescope, processed by Göran Nilsson. Total exposure time 1.1 hours.
  • NGC 246 acquired using the Schulman 0.8m Telescope atop Mount Lemmon, AZ. This is a full color (visual) image.
    NGC 246 acquired using the Schulman 0.8m Telescope atop Mount Lemmon, AZ. This is a full color (visual) image.

References

  1. ^ a b c d e "NGC 246". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2006-12-22.
  2. ^ a b "SEDS NGC Catalog Online". Results for NGC 246. Retrieved 2010-11-29.
  3. ^ "NGC 246". Astronomy: Stars & Planets. Retrieved 2013-01-07.
  4. ^ a b "The Night Sky", Astronomy Now, Oct 2008.
  5. ^ a b David H. Levy, Deep Sky Objects, Prometheus Books, 2005, ISBN 1-59102-361-0, p 129.
  6. ^ a b c information@eso.org. "Stars and Skulls: new ESO image reveals eerie nebula". www.eso.org. Retrieved 2023-03-09.
  7. ^ a b Stephen James O'Meara, The Caldwell Objects, Sky Publishing Corporation, ISBN 0-933346-97-2, p 223.
  8. ^ Adam, C.; Mugrauer, M. (2014-11-01). "HIP 3678: a hierarchical triple stellar system in the centre of the planetary nebula NGC 246". Monthly Notices of the Royal Astronomical Society. 444 (4): 3459–3465. arXiv:1409.5339. Bibcode:2014MNRAS.444.3459A. doi:10.1093/mnras/stu1677. ISSN 0035-8711.
  9. ^ "A hole in the heart of the Rosette Nebula". CNN. 14 February 2018.
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