The Dumbbell Nebula (also known as the Apple Core Nebula , Messier 27 , and NGC 6853 ) is a planetary nebula (nebulosity surrounding a white dwarf) in the constellation Vulpecula , at a distance of about 1360 light-years . It was the first such nebula to be discovered, by Charles Messier in 1764. At its brightness of visual magnitude 7.5 and diameter of about 8 arcminutes , it is easily visible in binoculars and is a popular observing target in amateur telescopes .
14-554: M27 , M.27 or M-27 may refer to: In science [ edit ] Messier 27 , a planetary nebula also called the Dumbbell Nebula In firearms and military equipment [ edit ] M27 Mosin–Nagant , a Finnish rifle M27 Infantry Automatic Rifle , a squad automatic weapon developed for the U.S. Marine Corps M27 link , a disintegrating 5.56×45mm NATO bullet link used in belt fed firearms M.27 (mountain gun) ,
28-482: A prolate spheroid and is viewed from our perspective along the plane of its equator. In 1992, Moreno-Corral et al. computed that its rate of expansion angularly was, viewed from our distance, no more than 2.3 arcseconds (″) per century. From this, an upper limit to the age of 14,600 years may be determined. In 1970, Bohuski, Smith, and Weedman found an expansion velocity of 31 km/s . Given its semi-minor axis radius of 1.01 ly , this implies that
42-651: A Norwegian mountain gun used in World War II M27 tank , a rejected US World War II medium tank design In transportation [ edit ] M27 motorway , a road connecting Cadnam and Portsmouth in Hampshire M27 highway (Russia) , a road connecting Novorossiysk and the border with Georgia M-27 (Michigan highway) , a road connecting I-75 near Indian River and US 23 and C-66 in Cheboygan Manitoba Highway 27 ,
56-416: A dark sky, just above the small constellation of Sagitta . Photoionization Photoionization is the physical process in which an ion is formed from the interaction of a photon with an atom or molecule . Not every interaction between a photon and an atom, or molecule, will result in photoionization. The probability of photoionization is related to the photoionization cross section of
70-722: A ground-state molecule and the target ion. This can be initialized by computing the vibrations of a molecule and associated cation (post ionization) using quantum chemical software e.g. QChem. For photon energies below the ionization threshold, the photoionization cross-section is near zero. But with the development of pulsed lasers it has become possible to create extremely intense, coherent light where multi-photon ionization may occur via sequences of excitations and relaxations. At even higher intensities (around 10 – 10 W/cm of infrared or visible light), non-perturbative phenomena such as barrier suppression ionization and rescattering ionization are observed. Several photons of energy below
84-513: A letter–number combination. If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=M27&oldid=1101200900 " Category : Letter–number combination disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Messier 27 The Dumbbell Nebula appears shaped like
98-624: A road connecting PTH 8 (McPhillips Rd.) and PTH 9 (Main St.) M27 (Johannesburg) , a Metropolitan Route in Johannesburg, South Africa M27 (Pretoria) , a Metropolitan Route in Pretoria, South Africa M27 (Durban) , a Metropolitan Route in Durban, South Africa [REDACTED] Topics referred to by the same term This disambiguation page lists articles associated with the same title formed as
112-424: The atom. The excess energy gives the released electron higher kinetic energy than the usual case of just-above threshold ionization. More precisely, the system will have multiple peaks in its photoelectron spectrum which are separated by the photon energies, indicating that the emitted electron has more kinetic energy than in the normal (lowest possible number of photons) ionization case. The electrons released from
126-457: The ionization threshold may actually combine their energies to ionize an atom. This probability decreases rapidly with the number of photons required, but the development of very intense, pulsed lasers still makes it possible. In the perturbative regime (below about 10 W/cm at optical frequencies), the probability of absorbing N photons depends on the laser-light intensity I as I . For higher intensities, this dependence becomes invalid due to
140-587: The kinematic age of the nebula is 9,800 years. Like many nearby planetary nebulae, the Dumbbell contains knots. Its central region is marked by a pattern of dark and bright cusped knots and their associated dark tails (see picture). The knots vary in appearance from symmetric objects with tails to rather irregular tail-less objects. Similarly to the Helix Nebula and the Eskimo Nebula , the heads of
154-430: The knots have bright cusps which are local photoionization fronts. The central star, a white dwarf progenitor, is estimated to have a radius which is 0.055 ± 0.02 R ☉ (0.13 light seconds) which gives it a size larger than most other known white dwarfs. Its mass was estimated in 1999 by Napiwotzki to be 0.56 ± 0.01 M ☉ . The Dumbbell nebula can be easily seen in binoculars in
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#1732772855447168-412: The species – the probability of an ionization event conceptualized as a hypothetical cross-sectional area. This cross section depends on the energy of the photon (proportional to its wavenumber) and the species being considered i.e. it depends on the structure of the molecular species. In the case of molecules, the photoionization cross-section can be estimated by examination of Franck-Condon factors between
182-418: The target will have approximately an integer number of photon-energies more kinetic energy. When either the laser intensity is further increased or a longer wavelength is applied as compared with the regime in which multi-photon ionization takes place, a quasi-stationary approach can be used and results in the distortion of the atomic potential in such a way that only a relatively low and narrow barrier between
196-414: The then occurring AC Stark effect . Resonance-enhanced multiphoton ionization (REMPI) is a technique applied to the spectroscopy of atoms and small molecules in which a tunable laser can be used to access an excited intermediate state . Above-threshold ionization (ATI) is an extension of multi-photon ionization where even more photons are absorbed than actually would be necessary to ionize
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