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[1]

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]

References

  1. 1 2 3 4 5 "NGC 246". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2006-12-22.
  2. 1 2 "SEDS NGC Catalog Online". Results for NGC 246. Retrieved 2010-11-29.
  3. ↑ "NGC 246". Astronomy: Stars & Planets. Retrieved 2013-01-07.
  4. 1 2 "The Night Sky", Astronomy Now, Oct 2008.
  5. 1 2 David H. Levy, Deep Sky Objects, Prometheus Books, 2005, ISBN 1-59102-361-0, p 129.
  6. 1 2 3 information@eso.org. "Stars and Skulls: new ESO image reveals eerie nebula". www.eso.org. Retrieved 2023-03-09.
  7. 1 2 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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