Keyhole Nebula

Keyhole Nebula
Nebula
Keyhole Nebula imaged by European Southern Observatory, the bright star at lower left side is Eta Carinae
Observation data: J2000.0 epoch
Right ascension10h 44m 19.0s[1]
Declination−59° 53′ 21.0″[1]
Distance~8,000 ly   (~2,500[1] pc)
Apparent magnitude (V)+1.0[2]
ConstellationCarina
DesignationsKeyhole Nebula[3]

Keyhole Nebula is a prominent dark nebulosity and feature within the larger Carina Nebula, a vast emission nebula in the southern constellation of Carina.[4][5][6][7][8][9]

Observation

Keyhole Nebula is a small dark cloud of cold molecules and dust within the Carina Nebula, containing bright filaments of hot, fluorescing gas, silhouetted against the much brighter background nebula. The feature was first described in the 1830s by British astronomer John Herschel during observations from the Cape of Good Hope and he referred to it as a "lemniscate-oval vacuity" when first describing it, and subsequently referred to it simply as the "oval vacuity". The term lemniscate continued to be used to describe this portion of the nebula until popular astronomy writer Emma Converse described the shape of the nebula as "resembling a keyhole" in an 1873 Appleton's Journal article.[10][11][12][13] The name Keyhole Nebula then came into common use, sometimes for the Keyhole itself, sometimes to describe the whole of the Carina Nebula (signifying "the nebula that contains the Keyhole").[14][15]

The diameter of the Keyhole structure is approximately seven light-years (2.1 pc). Its appearance has changed significantly since it was first observed in 19th century, likely due to variations in ionizing radiation and stellar winds from nearby massive stars, particularly the hypergiant binary system Eta Carinae (adjacent to the Keyhole).[17] The Keyhole does not have its own NGC designation. It is sometimes erroneously called NGC 3324,[18] but that catalogue designation refers to a reflection and emission nebula just northwest of the Carina Nebula (or to its embedded star cluster).[19][20][21]

Characteristics

The structure includes regions of active star formation with extremely hot, massive O-type stars (roughly 10 times hotter and up to 100 times more massive than the Sun). A small Bok globule within it, photographed in detail by the Hubble Space Telescope, is nicknamed the Finger of God Globule for its finger-like projection, with light visibly radiating from its edges (especially the southern tip).[1]

Reference

  1. ^ a b c d "Light and Shadow in the Carina Nebula (NGC 3372) - NASA Science". 2000-02-03. Retrieved 2026-01-13.
  2. ^ Frommert, Hartmut & Kronberg, Christine (22 March 1998). "NGC 3372". SEDS.org. Archived from the original on 30 May 2016. Retrieved 26 November 2016.
  3. ^ "Keyhole Nebula". simbad.cds.unistra.fr. Retrieved 2025-12-19.
  4. ^ [email protected]. "The Carina Nebula *". www.eso.org. Retrieved 2026-01-13.
  5. ^ "Keyhole Nebula - NASA Science". 2022-01-19. Retrieved 2026-01-13.
  6. ^ "Eta Carinae, Keyhole Nebula, and Carina Nebula". Telescope Live. Retrieved 2026-01-13.
  7. ^ "Keyhole Nebula | National Air and Space Museum". airandspace.si.edu. 2020-04-24. Retrieved 2026-01-13.
  8. ^ "2MASS Showcase Caption: Keyhole Nebula". www.ipac.caltech.edu. Retrieved 2026-01-13.
  9. ^ [email protected]. "Light and shadow in the Carina Nebula". www.esahubble.org. Retrieved 2026-01-13.
  10. ^ Herschel, John Frederick William (1847). Results of astronomical observations made during the years 1834, 5, 6, 7, 8, at the Cape of Good Hope: Being the completion of a telescopic survey of the whole surface of the visible heavens, commenced in 1825. Vol. 1. London: Smith, Elder and Co. pp. 33–35. Bibcode:1847raom.book.....H. OCLC 5045340.
  11. ^ Herschel, John Frederick William (1864). "Catalogue of Nebulae and Clusters of Stars". Philosophical Transactions of the Royal Society of London. 154: 1–137. Bibcode:1864RSPT..154....1H. doi:10.1098/rstl.1864.0001.
  12. ^ Abbott, F. (1873). "Eta Argus". Astronomical Register. 11: 221–224. Bibcode:1873AReg...11..221A.
  13. ^ Converse, Emma M. (27 December 1873). "Eta Argûs". Appletons' Journal. 10 (249): 818.
  14. ^ Moore, Joseph Haines & Sanford, Roscoe Frank (1914). "The spectrum of η Carinae". Lick Observatory Bulletin. 8 (252): 55–61. Bibcode:1914LicOB...8...55M. doi:10.5479/ADS/bib/1914LicOB.8.55M.
  15. ^ Burnham, Jr, Robert (1978). Burnham's Celestial Handbook. New York: Dover. p. 467. ISBN 978-0-486-23567-7.
  16. ^ "The Carina Nebula: Star Birth in the Extreme". The Hubble Heritage Project. Space Telescope Science Institute. 24 April 2007. Retrieved 14 August 2023.
  17. ^ Walborn, N. R. & Ingerson, T. E. (July 1977). "Structure in the Carina Nebula and Eta Carinae". Sky and Telescope. 54: 22–24. Bibcode:1977S&T....54...22W.
  18. ^ APOD – NGC 3324
  19. ^ Cooper, Ian; et al. (2008). The Night Sky Observer's Guide. Volume 3: The Southern Skies. Willmann-Bell. p. 52. ISBN 978-0-943396-89-7.
  20. ^ "NGC 3324". The NGC/IC Project. Archived from the original on 28 May 2009. Retrieved 17 May 2014.
  21. ^ "NGC 3324". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 17 May 2014.
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