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Encyclopedia > Nebula
The Triangulum Emission Nebula NGC 604
The Triangulum Emission Nebula NGC 604
The "Pillars of Creation" from the Eagle Nebula
The "Pillars of Creation" from the Eagle Nebula

A nebula (from Latin: "mist" [1]; pl. nebulae or nebulæ, with ligature or nebulas) is an interstellar cloud of dust, hydrogen gas and plasma. It is the first stage of a star's cycle. Originally nebula was a general name for any extended astronomical object, including galaxies beyond the Milky Way (some examples of the older usage survive; for example, the Andromeda Galaxy was referred to as the Andromeda Nebula before galaxies were discovered by Edwin Hubble). Nebulae often form star-forming regions, such as in the Eagle Nebula. This nebula is depicted in one of NASA's most famous images, the "Pillars of Creation". In these regions the formations of gas, dust and other materials 'clump' together to form larger masses, which attract further matter, and eventually will become big enough to form stars. The remaining materials are then believed to form planets, and other planetary system objects. Download high resolution version (1127x1201, 2479 KB) Wikipedia does not have an article with this exact name. ... Download high resolution version (1127x1201, 2479 KB) Wikipedia does not have an article with this exact name. ... Categories: Astronomy stubs | Nebulae | NGC objects ... Download high resolution version (935x920, 128 KB)Star forming pillars in the Eagle Nebula, as seen by the Hubble Space Telescopes WFPC2. ... Download high resolution version (935x920, 128 KB)Star forming pillars in the Eagle Nebula, as seen by the Hubble Space Telescopes WFPC2. ... The Eagle Nebula (also known as Messier Object 16, M16 or NGC 6611), perhaps one of the most famous and easily recognized space objects, is a young open cluster of stars in the constellation Serpens, discovered by Jean-Philippe de Cheseaux in 1745-46. ... A nebula in the astronomical sense of the word Nebula may refer to: Nebula - an astronomical term for a cloud of gas and dust in space. ... For other uses, see Latins and Latin (disambiguation). ... For Æ, the Irish writer, see George William Russell. ... Interstellar cloud is the generic name given to an accumulation of gas, plasma and dust in our and other galaxies. ... “Space dust” redirects here. ... This article is about the chemistry of hydrogen. ... For other uses, see Plasma. ... This article is about the astronomical object. ... For other uses, see Astronomy (disambiguation). ... Astronomical objects are significant physical entities, associations or structures which current science has confirmed to exist in space. ... For other uses, see Galaxy (disambiguation). ... For other uses, see Milky Way (disambiguation). ... The Andromeda Galaxy (IPA: , also known as Messier 31, M31, or NGC 224; often referred to as the Great Andromeda Nebula in older texts) is a spiral galaxy approximately 2. ... Andromeda Chained to the Rock by the Nereids (1840) Théodore Chassériau, Louvre Andromeda was a woman from Greek mythology who was chained to a rock to be a sacrifice to a sea monster as divine punishment for her mothers bragging. ... Edwin Powell Hubble (November 20, 1889 – September 28, 1953) was an American astronomer. ... The Eagle Nebula (also known as Messier Object 16, M16 or NGC 6611), perhaps one of the most famous and easily recognized space objects, is a young open cluster of stars in the constellation Serpens, discovered by Jean-Philippe de Cheseaux in 1745-46. ... For other uses, see NASA (disambiguation). ... The Eagle Nebula (also known as Messier Object 16, M16 or NGC 6611), perhaps one of the most famous and easily recognized space objects, is a young open cluster of stars in the constellation Serpens, discovered by Jean-Philippe de Cheseaux in 1745-46. ... This article is about the astronomical term. ... An artists concept of a planetary system A planetary system consists of the various non-stellar objects orbiting a star such as planets, moons, asteroids, meteoroids, comets, and cosmic dust. ...

Contents

Formation

NGC 2024, The Flame Nebula
NGC 2024, The Flame Nebula
NGC 6611, or the Eagle Nebula
NGC 6611, or the Eagle Nebula

Many nebulae form from the gravitational collapse of diffuse gas in the interstellar medium or ISM. As the material collapses under its own weight, massive stars may form in the center, and their ultraviolet radiation ionises the surrounding gas, making it visible at optical wavelengths. An example of this type of nebula is the Rosette Nebula or the Pelican Nebula. The size of these nebulae, known as HII regions, varies depending on the size of the original cloud of gas, and the number of stars formed can vary too. As the sites of star formation, the formed stars are sometimes known as a young, loose cluster. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... NGC2024 or the Flame Nebula is near the easternmost star in Orions Belt, Alnitak. ... The Eagle Nebula (also known as Messier Object 16, M16 or NGC 6611), perhaps one of the most famous and easily recognized space objects, is a young open cluster of stars in the constellation Serpens, discovered by Jean-Philippe de Cheseaux in 1745-46. ... Gravity is a force of attraction that acts between bodies that have mass. ... The interstellar medium (or ISM) is the name astronomers give to the tenuous gas and dust that pervade interstellar space. ... Note: Ultraviolet is also the name of a 1998 UK television miniseries about vampires. ... This article is about the electrically charged particle. ... For other uses, see Wavelength (disambiguation). ... Embedded in the center of the Rosette Nebula is an open cluster. ... The Pelican Nebula (also known as IC 5070) is an H II region associated with the North America Nebula in the constellation Cygnus. ...


Some nebulae are formed as the result of supernova explosions, the death throes of massive, short-lived stars. The material thrown off from the supernova explosion is ionised by the supernova remnant. One of the best examples of this is the Crab Nebula, in Taurus. It is the result of a recorded supernova in the year 1054 and at the centre of the nebula is a neutron star, created during the explosion. For other uses, see Supernova (disambiguation). ... For other uses, see Supernova (disambiguation). ... The Crab Nebula (catalogue designations M 1, NGC 1952, Taurus A) is a supernova remnant in the constellation of Taurus. ... Taurus (IPA: , Latin: , symbol , ) is one of the constellations of the zodiac. ... For the story by Larry Niven, see Neutron Star (story). ...


Other nebulae may form as planetary nebulae. This is the final stage of a low-mass star's life, like Earth's Sun. Stars with a mass up to 8-10 solar masses evolve into red giants and slowly lose their outer layers during pulsations in their atmospheres. When a star has lost a sufficient amount of material, its temperature increases and the ultraviolet radiation it emits is capable of ionizing the surrounding nebula that it has thrown off. NGC 6543, the Cats Eye Nebula A planetary nebula is an astronomical object consisting of a glowing shell of gas formed by certain types of stars at the end of their lives. ... This article is about Earth as a planet. ... Sol redirects here. ... This article is about the astronomical object. ... For other uses, see Mass (disambiguation). ... According to the Hertzsprung-Russell diagram, a red giant is a large non-main sequence star of stellar classification K or M; so-named because of the reddish appearance of the cooler giant stars. ... This article is about the electrically charged particle. ...


Diffuse nebulae

The Omega Nebula, an example of an emission nebula.
The Omega Nebula, an example of an emission nebula.
The Pleiades. The diffuse nebulae near the stars are examples of reflection nebula.
The Pleiades. The diffuse nebulae near the stars are examples of reflection nebula.

Most nebulae can be described as diffuse nebulae, which means that they are extended and contain no well-defined boundaries.[1] In visible light these nebulae may be divided into emission nebulae and reflection nebulae, a categorization that depends on how the light we see is created. Emission nebulae contain ionized gas (mostly ionized hydrogen) that produces spectral line emission.[2] These emission nebulae are often called HII regions; the term "HII" is used in professional astronomy to refer to ionized hydrogen. In contrast to emission nebulae, reflection nebulae do not produce significant amounts of visible light by themselves but instead reflect light from nearby stars.[2] Image File history File linksMetadata Size of this preview: 739 × 600 pixels Full resolution (2163 × 1756 pixel, file size: 276 KB, MIME type: image/jpeg) M17 at ESA/Hubble description Omega Nebula, also known as M17 source http://hubblesite. ... Image File history File linksMetadata Size of this preview: 739 × 600 pixels Full resolution (2163 × 1756 pixel, file size: 276 KB, MIME type: image/jpeg) M17 at ESA/Hubble description Omega Nebula, also known as M17 source http://hubblesite. ... The Omega Nebula (also known as the Swan Nebula, the Horseshoe Nebula, the Lobster Nebula, M17, and NGC 6618) is an H II region in the constellation Sagittarius. ... An emission nebula is a cloud of ionized gas ( a plasma) emitting light of various colors. ... Image File history File linksMetadata Download high-resolution version (4877x3515, 2034 KB) The Pleiades. ... Image File history File linksMetadata Download high-resolution version (4877x3515, 2034 KB) The Pleiades. ... A shorter exposure shows less nebulosity. ... The Witch Head reflection nebula (IC2118), about 1000 light years from earth, is associated with the bright star Rigel in the constellation Orion. ... The Orion Nebula, a famous emission nebula. ... An emission nebula is a cloud of ionized gas ( a plasma) emitting light of various colors. ... The Witch Head reflection nebula (IC2118), about 1000 light years from earth, is associated with the bright star Rigel in the constellation Orion. ... This article is about the electrically charged particle. ... This article is about the chemistry of hydrogen. ... A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from an excess or deficiency of photons in a narrow frequency range, compared with the nearby frequencies. ... NGC 604, a giant H II region in the Triangulum Galaxy. ...

The Horsehead Nebula, an example of a dark nebula.
The Horsehead Nebula, an example of a dark nebula.

Dark nebulae are similar to diffuse nebulae, but they are not seen by their emitted or reflected light. Instead, they are seen as dark clouds in front of more distant stars or in front of emission nebulae.[2] Download high resolution version (2546x1854, 212 KB)The Horsehead Nebula (Barnard 33). ... Download high resolution version (2546x1854, 212 KB)The Horsehead Nebula (Barnard 33). ... See also Horsehead Nebula for the place in The Hitchhikers Guide to the Galaxy. ... Dark Nebula Dark Nebula (Dark Zero in the original Japanese version) is a fictional character in the Kirby series of video games for Nintendo. ...


Although these nebulae appear different at optical wavelengths, they all appear to be bright sources of emission at infrared wavelengths. This emission comes primarily from the dust within the nebulae.[2] For other uses, see Infrared (disambiguation). ... “Space dust” redirects here. ...

Specific types of nebulae

While diffuse nebulae have poorly-defined boundaries, a few nebulae may actually be described as discrete objects with identifiable boundaries.


Planetary nebulae

The Cat's Eye Nebula, an example of a planetary nebula.
The Cat's Eye Nebula, an example of a planetary nebula.

Planetary nebulae are nebulae that form from the gaseous shells that are ejected from low-mass asymptotic giant branch stars when they transform into white dwarfs.[2] These nebulae are emission nebulae with spectral emission that is similar to the emission nebulae found in star formation regions.[2] Technically, they are a type of HII region because the majority of hydrogen will be ionised. However, planetary nebulae are denser and more compact than the emission nebulae in star formation regions.[2] Planetary nebulae are so called because the first astronomers who observed these objects thought that the nebulae resembled the disks of planets, although they are not at all related to planets.[3] Download high resolution version (800x874, 64 KB)X-ray/optical composite image of NGC 6543, the Cats Eye Nebula (X-ray: NASA/UIUC/Y.Chu et al. ... Download high resolution version (800x874, 64 KB)X-ray/optical composite image of NGC 6543, the Cats Eye Nebula (X-ray: NASA/UIUC/Y.Chu et al. ... The Cats Eye Nebula (NGC 6543) is a planetary nebula in the constellation of Draco. ... NGC 6543, The Cats Eye Nebula NGC 6853, The Dumbbell Nebula A planetary nebula is an astronomical object consisting of a glowing shell of gas and plasma formed by certain types of stars at the end of their lives. ... NGC 6543, The Cats Eye Nebula NGC 6853, The Dumbbell Nebula A planetary nebula is an astronomical object consisting of a glowing shell of gas and plasma formed by certain types of stars at the end of their lives. ... This article or section does not adequately cite its references or sources. ... Star formation is the process by which dense parts of molecular clouds collapse into a ball of plasma to form a star. ... This article is about the chemistry of hydrogen. ... For other uses, see Astronomy (disambiguation). ...

Protoplanetary nebula

A protoplanetary nebula (PPN) is an astronomical object which is at the short-lived episode during a star's rapid stellar evolution between the late asymptotic giant branch (LAGB) phase and the subsequent planetary nebula (PN) phase.[4] A PPN emits strong in infrared radiation, and is a kind of reflection nebula. The exact point when a PPN becomes a planetary nebula (PN) is defined by the temperature of the central star. Image File history File links PIA04533. ... Image File history File links PIA04533. ... The Red Rectangle nebula, so called because of its unique shape and color, is a nebula near the Monoceros constellation. ... The Egg Nebula, a protoplanetary nebula in Cygnus A protoplanetary nebula (PPN) is an astronomical object which is formed as a star evolves into a planetary nebula. ... The Egg Nebula, a protoplanetary nebula in Cygnus A protoplanetary nebula (PPN) is an astronomical object which is formed as a star evolves into a planetary nebula. ... Projected timeline of the Suns life In astronomy, stellar evolution is the process by which a star undergoes a sequence of radical changes during its lifetime. ... A period of Stellar evolution undertaken by all low to intermediate mass stars (0. ...

Supernova remnants

The Crab Nebula, an example of a supernova remnant.
The Crab Nebula, an example of a supernova remnant.

A supernova occurs when a high-mass star reaches the end of its life. When nuclear fusion ceases in the core of the star, the star collapses inward on itself. The gas falling inward either rebounds or gets so strongly heated that it expands outwards from the core, thus causing the star to explode.[2] The expanding shell of gas form a supernova remnant, a special type of diffuse nebula.[2] Although much of the optical and X-ray emission from supernova remnants originates from ionized gas, a substantial amount of the radio emission is a form of non-thermal emission called synchrotron emission.[2] This emission originates from high-velocity and electrons oscillating within magnetic fields.If the star cannot support itself, it can form a black hole, or also a gamma ray burst Image File history File linksMetadata Download high resolution version (2224x2212, 3149 KB) Summary Image: A Giant Hubble Mosaic of the Crab Nebula Source: http://hubblesite. ... Image File history File linksMetadata Download high resolution version (2224x2212, 3149 KB) Summary Image: A Giant Hubble Mosaic of the Crab Nebula Source: http://hubblesite. ... The Crab Nebula (catalogue designations M 1, NGC 1952, Taurus A) is a supernova remnant in the constellation of Taurus. ... Remnant of Keplers Supernova, SN 1604 Remnant of Tychos Nova, SN 1572 A supernova remnant (SNR) is the structure resulting from the gigantic explosion of a star in a supernova. ... For other uses, see Supernova (disambiguation). ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing sustainable fusion power. ... Remnant of Keplers Supernova, SN 1604 Remnant of Tychos Nova, SN 1572 A supernova remnant (SNR) is the structure resulting from the gigantic explosion of a star in a supernova. ... The Orion Nebula, a famous emission nebula. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... Synchrotron radiation is electromagnetic radiation, similar to cyclotron radiation, but generated by the acceleration of ultrarelativistic (i. ... Properties The electron (also called negatron, commonly represented as e−) is a subatomic particle. ... For the indie-pop band, see The Magnetic Fields. ...

Notable named nebulae

The Eagle Nebula (also known as Messier Object 16, M16 or NGC 6611), perhaps one of the most famous and easily recognized space objects, is a young open cluster of stars in the constellation Serpens, discovered by Jean-Philippe de Cheseaux in 1745-46. ... The Eta Carinae Nebula (also known as the Great Nebula in Carina, the Carina Nebula, or NGC 3372) is a large bright nebula that surrounds several open clusters of stars. ... The Orion Nebula (also known as Messier 42, M42, or NGC 1976) is a diffuse nebula situated south of Orions Belt. ... The Engraved Hourglass Nebula (also known as MyCn 18) is a young planetary nebula situated in the southern constellation Musca about 8,000 light-years away from Earth. ... See also Horsehead Nebula for the place in The Hitchhikers Guide to the Galaxy. ... Embedded in the center of the Rosette Nebula is an open cluster. ... The Ring Nebula (also known as the Messier 57 or NGC 6720) is located in the constellation Lyra. ... The Crab Nebula (catalogue designations M 1, NGC 1952, Taurus A) is a supernova remnant in the constellation of Taurus. ... The Cats Eye Nebula (NGC 6543) is a planetary nebula in the constellation of Draco. ... Barnards Loop (catalogue designation Sh 2-276) is an emission nebula in the constellation of Orion. ... The Red Square Nebula is a celestial object located in the area of the sky occupied by star MWC 922. ... The Tarantula Nebula. ... The Boomerang Nebula. ...

See also

Timeline of the interstellar medium and intergalactic medium 1848 - Lord Rosse studies M1 and names it the Crab Nebula 1864 - William Huggins studies the spectrum of the Orion Nebula and shows that it is a cloud of gas 1927 - Ira Bowen explains unidentified spectral lines from space as forbidden transition... A picture of Barnards Loop, which is a primary component of the nebula complex. ... The Large Magellanic Cloud (LMC) is a nearby satellite galaxy of our own galaxy, the Milky Way. ... The two Magellanic Clouds are irregular dwarf galaxies that may be orbiting our Milky Way galaxy[1], and thus are members of our Local Group of galaxies. ... The Small Magellanic Cloud (SMC) is a dwarf galaxy[1] in orbit around the Milky Way Galaxy. ... An H I region (pronounced aitch one region) is an interstellar cloud composed of neutral atomic hydrogen (H1). ... NGC 604, a giant H II region in the Triangulum Galaxy. ... The Messier objects are a set of astronomical objects catalogued by Charles Messier in his catalogue of Nebulae and Star Clusters first published in 1774. ...

References

  1. ^ The Messier Catalog: Diffuse Nebulae. University of Illinois SEDS. Retrieved on 2007-06-12.
  2. ^ a b c d e f g h i j F. H. Shu (1982). The Physical Universe. Mill Valley, California: University Science Books. ISBN 0-935702-05-9. 
  3. ^ E. Chaisson, S. McMillan (1995). Astronomy: a beginner's guide to the universe, 2nd, Upper Saddle River, New Jersey: Prentice-Hall. ISBN 0-13-733916-X. 
  4. ^ R. Sahai, C. Sánchez Contreras, M. Morris (2005). "A Starfish Preplanetary Nebula: IRAS 19024+0044". Astrophysical Journal 620: 948-960. doi:10.1086/426469. 

Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 163rd day of the year (164th in leap years) in the Gregorian calendar. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ...

Further reading

Lightner, G. Samuel. "Nebulae: Fuzzy Patches in Space." FusedWed.pppl.gov/CPEP 18 December 2000.


---. "Nebulae." FusedWed.pppl.gov/CPEP 17 November 2005.


---. "Reflection Nebulae." FusedWed.pppl.gov/CPEP 18 December 2000.


---. "Emission Nebulae." FusedWed.pppl.gov/CPEP 18 December 2000.


---. "Planetary Nebulae." FusedWed.pppl.gov/CPEP 18 December 2000.


---. "Supernova Remnants." FusedWed.pppl.gov/CPEP18 December 2000.


External links

Wikimedia Commons has media related to:
Nebula
  • fusedweb.pppl.gov
  • Information on star formation
  • Clickable table of Messier objects

  Results from FactBites:
 
Nebula - LoveToKnow 1911 (1858 words)
An enumeration of nebulae was made by Charles Messier in Paris in 1771, who recorded 103; Sir William Herschel increased the number known to over 250o; whilst Sir John Herschel between 1825 and 1847 catalogued and described 3926 nebulae (including 1700 observed at the Cape of Good Hope).
Nebulae may be conveniently classified according to their telescopic appearance; we enumerate below some of the principal forms that have been recognized, but it must be observed that this classification is rather superficial, and that the differentiation is often one of appearance only and not of real structure.
The typical spiral nebulae are in the form of a double spiral, the two branches of which proceed from diametrically opposite points of a bright nucleus and wind round it in the same sense; the whole is generally studded with points of condensation.
nebula. The Columbia Encyclopedia, Sixth Edition. 2001-07 (415 words)
In 1864, William Huggins confirmed William Herschel’s conclusion that nebulae are not swarms of stars by determining that the spectra of nebulae are made of bright lines characteristic of radiating gases.
Some bright nebulae, composed primarily of hydrogen gas ionized by nearby hot blue-white stars, radiate their own light; they are called emission nebulae and are characterized by narrow spectral emission lines.
Dark nebulae are detected as empty patches in a field of stars or as dark clouds obscuring part of a bright nebula in the background, as in the case of the Horsehead Nebula.
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