A nebula (from Latin: "mist" [1]; pl. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. nebulae or nebulæ, with ligature or nebulas) is an interstellar cloud of dust, hydrogen gas and plasma. Æ ( minuscule: æ) is a Grapheme formed from the letters A and E. Interstellar cloud is the generic name given to an accumulation of gas plasma and dust in our and other galaxies. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 In Physics and Chemistry, plasma is an Ionized Gas, in which a certain proportion of Electrons are free rather than being bound It is the first stage of a star's cycle. A star is a massive luminous ball of plasma. The nearest star to Earth is the Sun, which is the source of most of the Energy on Earth 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). Astronomy (from the Greek words astron (ἄστρον "star" and nomos (νόμος "law" is the scientific study s are significant physical entities, associations or structures which current Science has confirmed to exist in Space. A galaxy is a massive gravitationally bound system consisting of Stars an Interstellar medium of gas and dust, and Dark matter The Milky Way (a translation of the Latin Via Lactea, in turn derived from the Greek Γαλαξίας (Galaxias sometimes referred to simply The Andromeda Galaxy (ænˈdrɒmədə also known as Messier 31, M31, or NGC 224; often referred to as the Great Andromeda Andromeda was a woman from Greek mythology who as divine punishment for her mother's bragging was chained to a rock as a sacrifice to a sea monster Edwin Powell Hubble ( November 20, 1889 – September 28, 1953) was an American astronomer. Nebulae often form star-forming regions, such as in the Eagle Nebula. For an object in the constellation of Canis Major also called Eagle nebula see Seagull Nebula. This nebula is depicted in one of NASA's most famous images, the "Pillars of Creation". The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program For an object in the constellation of Canis Major also called Eagle nebula see Seagull Nebula. 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. A planet, as defined by the International Astronomical Union (IAU is a celestial body Orbiting a Star or stellar remnant that is
Contents |
Formation
Many nebulae form from the gravitational collapse of diffuse gas in the interstellar medium or ISM. The Flame Nebula, designated as NGC 2024, is in the Constellation Orion. For an object in the constellation of Canis Major also called Eagle nebula see Seagull Nebula. Gravitation is a natural Phenomenon by which objects with Mass attract one another 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. Ultraviolet ( UV) light is Electromagnetic radiation with a Wavelength shorter than that of Visible light, but longer than X-rays An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge In Physics wavelength is the distance between repeating units of a propagating Wave of a given Frequency. An example of this type of nebula is the Rosette Nebula or the Pelican Nebula. The Rosette Nebula is a large circular H II region located near one end of a giant molecular cloud in the Monoceros region of the Milky Way Galaxy The Pelican Nebula (also known as IC5070 and IC5067) is an H II region associated with the North America Nebula in the Constellation 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.
Some nebulae are formed as the result of supernova explosions, the death throes of massive, short-lived stars. A supernova (plural supernovae or supernovas) is a stellar Explosion. The material thrown off from the supernova explosion is ionised by the supernova remnant. A supernova (plural supernovae or supernovas) is a stellar Explosion. One of the best examples of this is the Crab Nebula, in Taurus. The Crab Nebula (catalogue designations M 1 NGC 1952 Taurus A is a Supernova remnant and Pulsar wind nebula in the Constellation Taurus (it looks like a bull (ˈtɔrəs bull, symbol, Unicode ♉ is one of the Constellations of the Zodiac. 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. A neutron star is a type of remnant that can result from the Gravitational collapse of a massive Star during a Type II, Type Ib or Type
Other nebulae may form as planetary nebulae. A planetary nebula is an Emission nebula consisting of a glowing shell of Gas and plasma formed by certain types of Stars when they die This is the final stage of a low-mass star's life, like Earth's Sun. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 The Sun (Sol is the Star at the center of the Solar System. 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. A star is a massive luminous ball of plasma. The nearest star to Earth is the Sun, which is the source of most of the Energy on Earth Mass is a fundamental concept in Physics, roughly corresponding to the Intuitive idea of how much Matter there is in an object A red giant is a luminous Giant star of low or intermediate mass (roughly 0 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. An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge
Diffuse nebulae
Most nebulae can be described as diffuse nebulae, which means that they are extended and contain no well-defined boundaries. In Astronomy, diffuse nebulae is the general term for illuminated Nebulae The three types of diffuse nebulae are Reflection nebulae Emission [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. An emission nebula is a Cloud of Ionized Gas ( ie a plasma) emitting light of various colors In Astronomy, reflection nebulae are clouds of dust which are simply reflecting the light of a nearby Star or stars Emission nebulae contain ionized gas (mostly ionized hydrogen) that produces spectral line emission. An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 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 [2] These emission nebulae are often called HII regions; the term "HII" is used in professional astronomy to refer to ionized hydrogen. An H II region (also known as Emission nebula) is a cloud of glowing Gas and plasma, sometimes several hundred Light-years across 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]
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]
Although these nebulae appear different at optical wavelengths, they all appear to be bright sources of emission at infrared wavelengths. Infrared ( IR) radiation is Electromagnetic radiation whose Wavelength is longer than that of Visible light, but shorter than that of This emission comes primarily from the dust within the nebulae. [2]
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
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. A planetary nebula is an Emission nebula consisting of a glowing shell of Gas and plasma formed by certain types of Stars when they die A white dwarf, also called a degenerate dwarf, is a small Star composed mostly of Electron-degenerate matter. [2] These nebulae are emission nebulae with spectral emission that is similar to the emission nebulae found in star formation regions. Star Formation is the process by which dense parts of Molecular clouds collapse into a ball of plasma to form a Star. [2] Technically, they are a type of HII region because the majority of hydrogen will be ionised. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 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. Astronomy (from the Greek words astron (ἄστρον "star" and nomos (νόμος "law" is the scientific study [3]
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. A protoplanetary nebula or preplanetary nebula (PPN is an Astronomical object which is at the short-lived episode during a Star 's rapid Stellar Stellar evolution is the process by which a Star undergoes a sequence of radical changes during its lifetime The asymptotic giant branch is the region of the Hertzsprung-Russell diagram populated by evolving low to medium-mass Stars This is a period of Stellar evolution [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.
Supernova remnants
A supernova occurs when a high-mass star reaches the end of its life. A supernova (plural supernovae or supernovas) is a stellar Explosion. When nuclear fusion ceases in the core of the star, the star collapses inward on itself. In Physics and Nuclear chemistry, nuclear fusion is the process by which multiple- like charged atomic nuclei join together to form a heavier nucleus 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. A supernova remnant ( SNR) is the structure resulting from the gigantic explosion of a Star in a Supernova. In Astronomy, diffuse nebulae is the general term for illuminated Nebulae The three types of diffuse nebulae are Reflection nebulae Emission [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. X-radiation (composed of X-rays) is a form of Electromagnetic radiation. Radio is the transmission of signals by Modulation of electromagnetic waves with frequencies below those of visible Light. This article concerns the physical phenomenon of synchrotron radiation [2] This emission originates from high-velocity and electrons oscillating within magnetic fields. The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J In Physics, a magnetic field is a Vector field that permeates space and which can exert a magnetic force on moving Electric charges If the star cannot support itself, it can form a black hole, or also a gamma ray burst
Notable named nebulae
- Eagle Nebula
- Eta Carinae Nebula
- Orion Nebula
- Hourglass Nebula
- Horsehead Nebula
- Rosette Nebula
- Ring Nebula
- Crab Nebula
- Cat's Eye Nebula
- Barnard's Loop
- Red Square Nebula
- Tarantula Nebula
- Boomerang Nebula
See also
- Timeline of the interstellar medium and intergalactic medium
- Orion Molecular Cloud Complex
- Large Magellanic Cloud
- Magellanic Clouds
- Small Magellanic Cloud
- H I region
- H II region
- Messier object
References
- ^ The Messier Catalog: Diffuse Nebulae. For an object in the constellation of Canis Major also called Eagle nebula see Seagull Nebula. The Carina Nebula (also known as the Great Nebula in Carina, the Eta Carinae Nebula, or NGC 3372) is a large bright Nebula that surrounds The Orion Nebula (also known as Messier 42, M42, or NGC 1976) is a Diffuse nebula situated south of Orion 's Belt The Engraved Hourglass Nebula (also known as MyCn 18) is a young Planetary nebula situated in the southern constellation Musca about 8000 Light-years The Horsehead Nebula (also known as Barnard 33 in bright nebula IC 434) is a Dark nebula in the Orion constellation. The Rosette Nebula is a large circular H II region located near one end of a giant molecular cloud in the Monoceros region of the Milky Way Galaxy The famously named " Ring Nebula " is located in the northern Constellation of Lyra, and also catalogued as Messier 57, M57 or The Crab Nebula (catalogue designations M 1 NGC 1952 Taurus A is a Supernova remnant and Pulsar wind nebula in the Constellation The Cat's Eye Nebula ( NGC 6543) is a Planetary nebula in the constellation of Draco. Barnard's 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 (also known as 30 Doradus, or NGC 2070) is an H II region in the Large Magellanic Cloud. The Boomerang Nebula (also called the Bow Tie Nebula) is a Protoplanetary nebula located 5000 light-years away from Earth in the Centaurus constellation Timeline of the Interstellar medium and Intergalactic medium 1848 - Lord Rosse studies M1 and names it The Orion Molecular Cloud Complex (also often referred to as simply the Orion Complex) refers to a large Nebula located in the Constellation of The Large Magellanic Cloud (LMC is a nearby Satellite galaxy of our own galaxy the Milky Way. History The Magellanic Clouds were certainly known since the earliest times by the ancient Middle Eastern peoples The Small Magellanic Cloud (SMC is a Dwarf galaxy. It contains several hundred million stars An H I region is an Interstellar cloud composed of neutral atomic Hydrogen (H I An H II region (also known as Emission nebula) is a cloud of glowing Gas and plasma, sometimes several hundred Light-years across The Messier objects are a set of Astronomical objects first listed by French astronomer Charles Messier in his "Catalogue des Nébuleuses University of Illinois SEDS. Retrieved on 2007-06-12. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1381 - Peasants' Revolt: in England, rebels arrive at Blackheath.
- ^ 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.
- ^ 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.
- ^ R. Sahai, C. Sánchez Contreras, M. Morris (2005). "A Starfish Preplanetary Nebula: IRAS 19024+0044". Astrophysical Journal 620: 948-960. doi:. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.
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
Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic