Carina Nebula

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Carina Nebula
Emission nebula
Carina Nebula.jpg
Detail of NGC 3372 taken by the VLT telescope
Credit: ESO
Observation data: J2000.0 epoch
Right ascension 10h 45m 08.5s[1]
Declination −59° 52′ 04″[1]
Distance ~6500-10000[1] ly
Apparent magnitude (V) +1.0
Constellation Carina
Physical characteristics
Radius ~460 [2] ly   (~140 pc)
Notable features Includes dark nebula
Keyhole Nebula
Designations NGC 3372,[3] ESO 128-EN013,[1] GC 2197,[1] Caldwell 92[4]
See also: Lists of nebulae

Coordinates: Sky map 10h 45m 08.5s, −59° 52′ 04″

The Carina Nebula (also known as the Great Nebula in Carina, the Eta Carinae Nebula, NGC 3372, as well as the Grand Nebula) is a large complex area of bright and dark nebulosity in the constellation of Carina, and is located in the Carina–Sagittarius Arm. The nebula lies at an estimated distance between 6,500 and 10,000 light years from Earth.

The nebula has within its boundaries the large OB association Carina OB1 and several related open clusters, including numerous O-type stars and several Wolf-Rayet stars. Carina OB1 encompasses the star clusters Trumpler 14 and Trumpler 16. Trumpler 14 is one of the youngest known star clusters, at half a million years old. Trumpler 16 is the home of WR 25, currently the most luminous star known in our Milky Way galaxy, together with the less luminous but more massive and famous Eta Carinae star system, and the O2 supergiant HD 93129A. Trumpler 15, Collinder 228, Collinder 232, NGC 3324, and NGC 3293 are also considered members of the association. NGC 3293 is the oldest and furthest from Trumpler 14, indicating sequential and ongoing star formation.

The nebula is one of the largest diffuse nebulae in our skies. Although it is some four times as large and even brighter than the famous Orion Nebula, the Carina Nebula is much less well known, due to its location in the southern sky. It was discovered by Nicolas Louis de Lacaille in 1751–52 from the Cape of Good Hope.

Objects within the Carina Nebula[edit]

Eta Carinae[edit]

Main article: Eta Carinae
Carina Nebula, glowing intensely red in the middle of the image.[5]

Eta Carinae is a highly luminous hypergiant star. Estimates of its mass range from 100 to 150 times the mass of the Sun, and its luminosity is about four million times that of the Sun.

This object is currently the most massive star that can be studied in great detail, because of its location and size. Several other known stars may be more luminous and more massive, but data on them is far less robust. (Caveat: Since examples such as the Pistol Star have been demoted by improved data, one should be skeptical of most available lists of "most massive stars." In 2006, Eta Carinae still had the highest confirmed luminosity, based on data across a broad range of wavelengths.) Stars with more than 80 times the mass of the Sun produce more than a million times as much light as the Sun. They are quite rare—only a few dozen in a galaxy as big as ours—and they flirt with disaster near the Eddington limit, i.e., the outward pressure of their radiation is almost strong enough to counteract gravity. Stars that are more than 120 solar masses exceed the theoretical Eddington limit, and their gravity is barely strong enough to hold in its radiation and gas, resulting in a possible supernova or hypernova in the near future.

Eta Carinae's effects on the nebula can be seen directly. The dark globules in the above image and some other less visible objects have tails pointing directly away from the massive star. The entire nebula would have looked very different before the Great Eruption in the 1840s surrounded Eta Carinae with dust, drastically reducing the amount of ultraviolet light it put into the nebula.

Homunculus Nebula[edit]

Main article: Homunculus Nebula

Within the large bright nebula is a much smaller feature, immediately surrounding Eta Carinae itself, known as the Homunculus Nebula (from the Latin meaning Little Man). It is believed to have been ejected in an enormous outburst in 1841 which briefly made Eta Carinae the second-brightest star in the sky.

Keyhole Nebula[edit]

Detail of the Keyhole Nebula, imaged by Hubble Space Telescope. The small nebula to the upper left has been nicknamed "finger of God" or "God's birdie", due to the gesture it appears to be making.

The Keyhole 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. John Herschel used the term "lemniscate-oval vacuity" when first describing it,[6] and subsequently referred to it simply as the "oval vacuity".[7] The term lemniscate continued to be used to describe this portion of the nebula[8] until popular astronomy writer Emma Converse described the shape of the nebula as "resembling a keyhole" in an 1873 Appleton's Journal article.[9] 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").[10][11]

The diameter of the Keyhole structure is approximately 7 light years. Its appearance has changed significantly since it was first observed, possibly due to changes in the ionising radiation from Eta Carinae.[12] The Keyhole does not have its own NGC designation. It is sometimes erroneously called NGC 3324,[13] but that catalogue designation refers to a reflection and emission nebula just northwest of the Carina Nebula (or to its embedded star cluster).[14][15][16]

Mystic Mountain[edit]

Main article: Mystic Mountain

The "Mystic Mountain" is an image of a dust–gas pillar in the Carina Nebula taken by Hubble Space Telescope on its 20th anniversary. The area was observed by Hubble’s Wide Field Camera 3 on February 1–2, 2010. The pillar measures three light years in height; nascent stars inside the pillar fire off gas jets, that stream from towering peaks.

Image gallery[edit]

Tour of the Carina Nebula.
Carina Nebula.
This video starts from a wide-field view of the constellation of Carina (The Keel), and zooms in to the Carina Nebula region.
This zoom sequence starts with a broad view of the Milky Way and closes in on the Carina Nebula. In the final sequence we see a new image taken in infrared light using the HAWK-I camera on ESO’s Very Large Telescope. Many previously hidden features, scattered across a spectacular celestial landscape of gas, dust and young stars, have emerged.
This video sequence compares a view of the Carina Nebula taken in visible light with a new picture taken in infrared light. The visible-light view comes from the MPG/ESO 2.2-metre telescope at the La Silla Observatory and the new infrared picture comes from the HAWK-I camera on ESO’s Very Large Telescope. Many new features that are not seen at all in visible light can be seen in great detail in the new sharp infrared image from the VLT.


  1. ^ a b c d e "Object Data – NGC 3372". The NGC/IC Project. Archived from the original on 2008-05-12. Retrieved 2008-04-25. 
  2. ^ "NGC 3372 - The Eta Carinae Nebula". Atlas of the Universe. Retrieved 2013-10-01. 
  3. ^ "NGC 3372". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2013-09-03. 
  4. ^ O'Meara, S. J. (2002). The Caldwell Objects. Cambridge University Press. pp. 361–369. ISBN 0-521-82796-5. 
  5. ^ "One Picture, Many Stories". ESO Picture of the Week. Retrieved 13 February 2013. 
  6. ^ 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. 1. London, United Kingdom: Smith, Elder and Co. pp. 33–35. 
  7. ^ Herschel, John Frederick William (1864). "Catalogue of Nebulae and Clusters of Stars". Philosophical Transactions of the Royal Society of London. 154: 1. Bibcode:1864RSPT..154....1H. doi:10.1098/rstl.1864.0001. 
  8. ^ Abbott, F. (1873). "Eta Argus". Astronomical register. 11: 221. Bibcode:1873AReg...11..221A. 
  9. ^ Appletons' Journal. D. Appleton and Company. 1873. pp. 818–. 
  10. ^ Moore, Joseph Haines; Sanford, Roscoe Frank (1914). "The spectrum of η Carinae". Lick Observatory bulletin ; no. 252; Lick Observatory bulletins ; no. 252. 8: 55. Bibcode:1914LicOB...8...55M. doi:10.5479/ADS/bib/1914LicOB.8.55M. 
  11. ^ See, e.g., Burnham's Celestial Handbook, Dover, 1978, p. 467.
  12. ^ Walborn, N. R.; Ingerson, T. E. (1977). "Structure in the Carina Nebula and Eta Carinae". Sky and Telescope. 54: 22. Bibcode:1977S&T....54...22W. 
  13. ^ For example, see APOD - NGC 3324.
  14. ^ Kepple; et al. (2008). The Night Sky Observer's Guide. Vol. 3. Willman Bell, Inc. p. 52. ISBN 9780943396897. 
  15. ^ "Results for NGC 3324". NGC/IC Project. Retrieved 17 May 2014. 
  16. ^ "NGC 3324". SIMBAD. Retrieved 17 May 2014. 

External links[edit]