The Carina Nebula or Eta Carinae Nebula (catalogued as NGC 3372; also known as the Great Carina Nebula) is a large, complex area of

bright Bright may refer to: Common meanings *Bright, an adjective meaning giving off or reflecting illumination; see Brightness *Bright, an adjective meaning someone with intelligence People * Bright (surname) * Bright (given name) *Bright, the stage na ...

and dark nebulosity in the constellation Carina, located in the

Carina–Sagittarius Arm The Carina–Sagittarius Arm (also known as the Sagittarius Arm or Sagittarius–Carina Arm, labeled -I) is generally thought to be a minor spiral arm of the Milky Way galaxy. Each spiral arm is a long, diffuse curving streamer of stars that radia ...

of the Milky Way galaxy. The nebula is approximately from

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

. The nebula has within its boundaries the large

Carina OB1 Carina OB1 is a giant OB association in the Carina Nebula, which is home to some of the most massive and luminous stars in the Milky Way Galaxy. It includes the young star clusters Collinder 228, NGC 3293, NGC 3324, IC 2581, Trumpler 14, T ...

association Association may refer to: *Club (organization), an association of two or more people united by a common interest or goal *Trade association, an organization founded and funded by businesses that operate in a specific industry *Voluntary associatio ...

and several related

open cluster An open cluster is a type of star cluster made of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, and ...

s, including numerous O-type stars and several

Wolf–Rayet star Wolf–Rayet stars, often abbreviated as WR stars, are a rare heterogeneous set of stars with unusual spectra showing prominent broad emission lines of ionised helium and highly ionised nitrogen or carbon. The spectra indicate very high surface ...

s. encompasses the

star cluster Star clusters are large groups of stars. Two main types of star clusters can be distinguished: globular clusters are tight groups of ten thousand to millions of old stars which are gravitationally bound, while open clusters are more loosely clust ...

s and . is one of the youngest known star clusters at half a million years old. is the home of , currently the most luminous star known in our

Milky Way The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye ...

galaxy A galaxy is a system of stars, stellar remnants, interstellar gas, dust, dark matter, bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System. ...

, together with the less luminous but more massive and famous Eta Carinae star system and the O2 supergiant . , , , , and are also considered members of the association. is the oldest and furthest from , indicating sequential and ongoing star formation. The nebula is one of the largest diffuse nebulae in our skies. Although it is four times as large as and even brighter than the famous

Orion Nebula The Orion Nebula (also known as Messier 42, M42, or NGC 1976) is a diffuse nebula situated in the Milky Way, being south of Orion's Belt in the constellation of Orion. It is one of the brightest nebulae and is visible to the naked eye in the nig ...

, the Carina Nebula is much less well known due to its location in the southern sky. It was discovered by

Nicolas-Louis de Lacaille Abbé Nicolas-Louis de Lacaille (; 15 March 171321 March 1762), formerly sometimes spelled de la Caille, was a kingdom of France, French astronomer and geodesist who named 14 out of the IAU designated constellations, 88 constellations. From 1750 ...

in 1752 from the

Cape of Good Hope The Cape of Good Hope ( af, Kaap die Goeie Hoop ) ;''Kaap'' in isolation: pt, Cabo da Boa Esperança is a rocky headland on the Atlantic coast of the Cape Peninsula in South Africa. A common misconception is that the Cape of Good Hope is t ...

. The Carina Nebula was selected as one of five cosmic objects observed by the

James Webb Space Telescope The James Webb Space Telescope (JWST) is a space telescope which conducts infrared astronomy. As the largest optical telescope in space, its high resolution and sensitivity allow it to view objects too old, distant, or faint for the Hubble Spa ...

, as part of the release of its first official science images. A detailed image was made of an early star-forming region of NGC 3324 known as the Cosmic Cliffs.

Discovery and basic information

discovered the nebula on 25 January 1752. Its dimensions are 120×120 arcminutes centered on the

coordinates In geometry, a coordinate system is a system that uses one or more numbers, or coordinates, to uniquely determine the position of the points or other geometric elements on a manifold such as Euclidean space. The order of the coordinates is sig ...

right ascension Right ascension (abbreviated RA; symbol ) is the angular distance of a particular point measured eastward along the celestial equator from the Sun at the March equinox to the (hour circle of the) point in question above the earth. When paired w ...

and

declination In astronomy, declination (abbreviated dec; symbol ''δ'') is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. Declination's angle is measured north or south of the ...

. In modern times it is calculated to be around from Earth.

Objects within the Carina Nebula

Eta Carinae

Eta Carinae is a highly luminous hypergiant

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

. Estimates of its

mass Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different elementar ...

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 The Eddington luminosity, also referred to as the Eddington limit, is the maximum luminosity a body (such as a star) can achieve when there is balance between the force of radiation acting outward and the gravitational force acting inward. The stat ...

, i.e., the outward pressure of their

radiation In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes: * ''electromagnetic radiation'', such as radio waves, microwaves, infrared, visi ...

is almost strong enough to counteract

gravity In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stro ...

. 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 A supernova is a powerful and luminous explosion of a star. It has the plural form supernovae or supernovas, and is abbreviated SN or SNe. This transient astronomical event occurs during the last evolutionary stages of a massive star or when ...

or hypernova in the near future. Eta Carinae's effects on the nebula can be seen directly. Dark globules 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 Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nanometer, nm (with a corresponding frequency around 30 Hertz, PHz) to 400 nm (750 Hertz, THz), shorter than that of visible light, but longer than ...

light it put into the nebula.

Homunculus Nebula

Within the large bright nebula is a much smaller feature, immediately surrounding Eta Carinae itself, known as the

Homunculus Nebula The Homunculus Nebula is a bipolar emission and reflection nebula surrounding the massive star system Eta Carinae, about () from Earth. The nebula is embedded within the much larger Carina Nebula, a large star-forming H II region. From the L ...

(from

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

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. The Homunculus Nebula is a small H II region, with gas shocked into ionized and excited states. It also absorbs much of the light from the extremely luminous central stellar system and re-radiates it as

infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

(IR). It is the brightest object in the sky at mid-IR wavelengths. The distance to the Homunculus can be derived from its observed angular dimensions and calculated linear size, assuming it is axially symmetric. The most accurate distance obtained using this method is . The largest radius of the bipolar lobes in this model is about 22,000 AU, and the axis is oriented 41° from the line of sight, or 49° relative to the plane of the sky, which means it is seen from Earth slightly more "end on" than "side on".

Keyhole Nebula

Keyhole in the Carina Nebula (eso0905a crop)

The Keyhole, or 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.

John Herschel Sir John Frederick William Herschel, 1st Baronet (; 7 March 1792 – 11 May 1871) was an English polymath active as a mathematician, astronomer, chemist, inventor, experimental photographer who invented the blueprint and did botanical wor ...

used the term "

lemniscate In algebraic geometry, a lemniscate is any of several figure-eight or -shaped curves. The word comes from the Latin "''lēmniscātus''" meaning "decorated with ribbons", from the Greek λημνίσκος meaning "ribbons",. or which alternativel ...

-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. 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"). The diameter of the Keyhole structure is approximately . Its appearance has changed significantly since it was first observed, possibly due to changes in the

ionizing radiation Ionizing radiation (or ionising radiation), including nuclear radiation, consists of subatomic particles or electromagnetic waves that have sufficient energy to ionize atoms or molecules by detaching electrons from them. Some particles can travel ...

from Eta Carinae. The Keyhole does not have its own NGC designation. It is sometimes erroneously called

NGC 3324 NGC 3324 is an open cluster in the southern constellation Carina, located northwest of the Carina Nebula at a distance of from Earth. It is closely associated with the emission nebula , also known as . The two are often confused as a single ob ...

, but that catalogue designation refers to a reflection and emission nebula just northwest of the Carina Nebula (or to its embedded star cluster).

Defiant Finger

A small Bok globule in the Keyhole Nebula (at RA 10h44m30s, Dec −59°40') has been photographed by the Hubble Space Telescope and is nicknamed the "Carina Defiant Finger" due to its shape. In Hubble images, light can be seen radiating off the edges of the globule; this is especially visible in the southern tip, where the "finger" is. It is thought that the Defiant Finger is being ionized by the bright Wolf–Rayet star WR 25, and/or Trumpler 16-244, a bright

blue supergiant A blue supergiant (BSG) is a hot, luminous star, often referred to as an OB supergiant. They have luminosity class I and spectral class B9 or earlier. Blue supergiants are found towards the top left of the Hertzsprung–Russell diagram, above an ...

. It has a mass of at least , and stars may be forming within it. Like other interstellar clouds under intense radiation, the Defiant Finger will eventually be completely evaporated; for this cloud the time frame is predicted to be 200,000 to 1,000,000 years.

Trumpler 14

Trumpler 14 is an open cluster with a diameter of , located within the inner regions of the Carina Nebula, approximately from Earth. It is one of the main clusters of the stellar association, which is the largest association in the Carina Nebula. About 2,000 stars have been identified in . and the total mass of the cluster is estimated to be .

Trumpler 15

Trumpler 15 is a star cluster on the north-east edge of the Carina Nebula. Early studies disagreed about the distance, but

astrometric Astrometry is a branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. It provides the kinematics and physical origin of the Solar System and this galaxy, the Milky Way. Histor ...

measurements by the ''Gaia'' mission have confirmed that it is the same distance as the rest of

Trumpler 16

Trumpler 16 is one of the main clusters of the

stellar association, which is the largest association in the Carina Nebula, and it is bigger and more massive than . The star Eta Carinae is part of this cluster.

Mystic Mountain

Mystic Mountain is the term for a dust–gas pillar in the Carina Nebula, a photo of which was taken by

Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versa ...

on its 20th anniversary. The area was observed by Hubble's

Wide Field Camera 3 The Wide Field Camera 3 (WFC3) is the Hubble Space Telescope's last and most technologically advanced instrument to take images in the visible spectrum. It was installed as a replacement for the Wide Field and Planetary Camera 2 during the first s ...

on 1–2 February 2010. The pillar measures in height; nascent stars inside the pillar fire off gas jets that stream from towering “peaks”.

WR 22

WR 22 is an eclipsing binary. The dynamical masses derived from orbital fitting vary from over to less than for the primary and about for the secondary. The spectroscopic mass of the primary has been calculated at or .

WR 25

WR 25 is a binary system in the central portion of the Carina Nebula, a member of the cluster. The primary is a Wolf–Rayet star, possibly the most luminous star in the galaxy. The secondary is hard to detect but thought to be a luminous OB star.

HD 93129

HD 93129 is a triple star system of O-class stars in Carina. All three stars of are among the most luminous in the galaxy; consists of two clearly resolved components, and , and itself is made up of two much closer stars. HD 93129 A has been resolved into two components. The spectrum is dominated by the brighter component, although the secondary is only 0.9 magnitudes fainter. is an O2 supergiant and Ab is an O3.5 main sequence star. Their separation has decreased from 55 milliarcseconds in 2004 to only 27 mas in 2013, but an accurate orbit is not available. HD 93129 B is an O3.5 main-sequence star 3

arcsecond A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The na ...

s away from the closer pair. It is about 1.5 magnitudes fainter than the combined , and is approximately the same brightness as .

HD 93250

HD 93250 is one of the brightest stars in the region of the Carina Nebula. It is only 7.5 arcminutes from Eta Carinae, and is considered to be a member of the same loose

, although it appears closer to the more compact . HD 93250 is known to be a binary star, however, individual spectra of the two components have never been observed but are thought to be very similar. The spectral type of has variously been given as O5, O6/7, O4, and O3. It has sometimes been classified as a

main sequence In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Her ...

star and sometimes as a giant star. The Galactic O-Star Spectroscopic Survey has used it as the standard star for the newly created O4 subgiant spectral type.

HD 93205

HD 93205 is a binary system of two large stars. The more massive member of the pair is an O3.5 main sequence star. The spectrum shows some ionized nitrogen and helium emission lines, indicating some mixing of fusion products to the surface and a strong

stellar wind A stellar wind is a flow of gas ejected from the upper atmosphere of a star. It is distinguished from the bipolar outflows characteristic of young stars by being less collimated, although stellar winds are not generally spherically symmetric. D ...

. The mass calculated from apsidal motion of the orbits is . This is somewhat lower than expected from evolutionary modelling of a star with its observed parameters. The less massive member is an O8 main sequence star of approximately . It moves in its orbit at a speed of over and is considered to be a relativistic binary, which causes the apses of the orbit to change in a predictable way.

Catalogued open clusters in Carina Nebula

, there are eight known open clusters in the Carina Nebula: *Bochum 10 (Bo 10) *Bochum 11 (Bo 11) *Collinder 228 (Cr 228) *Collinder 232 (Cr 232) *Collinder 234 (Cr 234) *Trumpler 14 (Tr 14, Cr 230) *Trumpler 15 (Tr 15, Cr 231) *Trumpler 16 (Tr 16, Cr 233)

Annotated map

Gallery

File:The spectacular star-forming Carina Nebula imaged by the VLT Survey Telescope.jpg, Overview of the Carina Nebula. The Keyhole is superimposed on the bright area above center, and Eta Carinae is the bright star just to its left. File:The Carina Nebula in infrared light.jpg, Carina Nebula in infrared light File:Nearby Supernova Factory Ramps Up- A star-forming region about 7,500 light years from Earth. (6261054663).jpg,

X-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...

s from stars and diffuse multimillion-Kelvin plasma light up the Carina Nebula in this

Chandra X-ray Observatory The Chandra X-ray Observatory (CXO), previously known as the Advanced X-ray Astrophysics Facility (AXAF), is a Flagship-class space telescope launched aboard the during STS-93 by NASA on July 23, 1999. Chandra is sensitive to X-ray sources 1 ...

image File:ESO - The Carina Nebula (by).jpg, Close-up of the Carina Nebula's central region File:Carina Nebula around the Wolf–Rayet star WR 22.jpg, Wolf–Rayet star WR 22 File:Hs-2007-16-e-800x800.jpg, Bok globule nicknamed "The Caterpillar" File:Region R44 in the Carina Nebula.jpg, Region R44 in the Carina Nebula

References

External links

Carina Nebula
at SEDS.org

at Atlas of the Universe
Carina Nebula
at Constellation Guide * {{DEFAULTSORT:Carina Nebula Carina (constellation) Carina–Sagittarius Arm H II regions 3372 092 Articles containing video clips 17520125 Star-forming regions