Astronomy:NGC 246

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Short description: Planetary nebula in the constellation Cetus
NGC 246
Emission nebula
Planetary nebula
NGC 246.jpg
An infrared Spitzer Space Telescope image of NGC 246.
Credit: NASA/JPL.
Observation data: J2000 epoch
Right ascension 00h 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]

Image gallery

  • 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.

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 "NGC 246". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=NGC+246. 
  2. ↑ 2.0 2.1 "SEDS NGC Catalog Online". Results for NGC 246. http://spider.seds.org/ngc/ngc.cgi?NGC+246. 
  3. ↑ "NGC 246". Astronomy: Stars & Planets. http://jumk.de/astronomie/special-stars/ngc-246.shtml. 
  4. ↑ 4.0 4.1 "The Night Sky", Astronomy Now, Oct 2008.
  5. ↑ 5.0 5.1 David H. Levy, Deep Sky Objects, Prometheus Books, 2005, ISBN:1-59102-361-0, p 129.
  6. ↑ 6.0 6.1 6.2 information@eso.org. "Stars and Skulls: new ESO image reveals eerie nebula" (in en). https://www.eso.org/public/news/eso2019/. 
  7. ↑ 7.0 7.1 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. doi:10.1093/mnras/stu1677. ISSN 0035-8711. Bibcode: 2014MNRAS.444.3459A. https://ui.adsabs.harvard.edu/abs/2014MNRAS.444.3459A. 
  9. ↑ "A hole in the heart of the Rosette Nebula". 14 February 2018. https://www.cnn.com/2018/02/14/world/rosette-nebula-heart/index.html. 

External links



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