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Wolf–Rayet Nebula
A Wolf–Rayet nebula is a nebula which surrounds a Wolf–Rayet star. WR nebulae have been classified in various ways. One of the earliest was by the nature and origin of the nebula: * HII regions * ejecta-type nebulae * wind-blown bubbles This classification requires detailed study of each nebula and more recent attempts have been made to allow quick classification of nebulae based purely on their appearance. WR nebulae frequently are ring-shaped in appearance, possibly spherical. Others are irregular, either disrupted shells or formed from clumpy ejection. Examples of this type of nebula include NGC 6888, NGC 2359, and NGC 3199. Some WR nebulae have a prominent spiral structure, for example the WR 104 WR 104 is a triple star system located about from Earth. The primary star is a Wolf–Rayet star (abbreviated as WR), which has a B0.5 main sequence star in close orbit and another more distant fainter companion. The WR star is surr ..., formerly securing the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LHA 115 - N 76A - Eso0310a
LHA may refer to: *Flughafen Lahr (IATA code) * LHA (for eading Helicopter Academies, "Raising flying standards in Europe" * LHA (for " Landing Helicopter Assault"), US Navy hull classification symbol for the general purpose helicopter-carrying amphibious assault ships of the ''America'' classes. * Lateral hypothalamic area, a part of the brain that has been implicated in the control of feeding behavior * Lesbian Herstory Archives, a New York–based lesbian history archive and museum. * Lha, a letter of Cyrillic alphabet * LHA (file format), a freeware compression utility and associated file format * Lincoln Highway Association * Livonia Hockey Association, amateur hockey league in Livonia, Michigan * LHA, the local hour angle of an astronomical object * Local Housing Allowance, welfare benefit in the UK to help tenants with low incomes pay their rent * Stock ticker for Lufthansa on the Frankfurt Stock Exchange * LaurenHill Academy LaurenHill Academy (LHA; french: Académie La ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
WR 31a
WR 31a, commonly referred to as Hen 3-519, is a Wolf–Rayet (WR) star in the southern constellation of Carina that is surrounded by an expanding Wolf–Rayet nebula. It is not a classical old stripped-envelope WR star, but a young massive star which still has some hydrogen left in its atmosphere. History of observations WR 31a was first published in 1952 as one of six peculiar emission line stars, but not given a designation at that time. It was described as having numerous P Cygni type lines with unusually broad emission components. A year later it was listed as being associated with nebulosity, at the time thought to be a planetary nebula. In 1976, it was included in a catalogue of southern emission-line stars, the third catalogue of emission objects compiled by Karl Gordon Henize. The designation , sometimes , was adopted as the most common identifier for this star. In 2001, it was listed in The Seventh Catalogue of Galactic Wolf-Rayet stars as entry 31a, but it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nebula
A nebula ('cloud' or 'fog' in Latin; pl. nebulae, nebulæ or nebulas) is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral or molecular hydrogen and also cosmic dust. Nebulae are often star-forming regions, such as in the "Pillars of Creation" in the Eagle Nebula. In these regions, the formations of gas, dust, and other materials "clump" together to form denser regions, which attract further matter, and eventually will become dense enough to form stars. The remaining material is then thought to form planets and other planetary system objects. Most nebulae are of vast size; some are hundreds of light-years in diameter. A nebula that is visible to the human eye from Earth would appear larger, but no brighter, from close by. The Orion Nebula, the brightest nebula in the sky and occupying an area twice the angular diameter of the full Moon, can be viewed with the naked eye but was missed by early astronomers. Although denser than the space ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 enhancement of heavy elements, depletion of hydrogen, and strong stellar winds. The surface temperatures of known Wolf–Rayet stars range from 20,000 K to around 210,000 K, hotter than almost all other kinds of stars. They were previously called W-type stars referring to their spectral classification. Classic (or population I) Wolf–Rayet stars are evolved, massive stars that have completely lost their outer hydrogen and are fusing helium or heavier elements in the core. A subset of the population I WR stars show hydrogen lines in their spectra and are known as WNh stars; they are young extremely massive stars still fusing hydrogen at the core, with helium and nitrogen exposed at the surface by strong mixing and radia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HII Region
An H II region or HII region is a region of interstellar atomic hydrogen that is ionized. It is typically in a molecular cloud of partially ionized gas in which star formation has recently taken place, with a size ranging from one to hundreds of light years, and density from a few to about a million particles per cubic centimetre. The Orion Nebula, now known to be an H II region, was observed in 1610 by Nicolas-Claude Fabri de Peiresc by telescope, the first such object discovered. The regions may be of any shape because the distribution of the stars and gas inside them is irregular. Hertzsprung-Russell diagram, The short-lived blue stars created in these regions emit copious amounts of ultraviolet light that ionize the surrounding gas. H II regions—sometimes several hundred light-years across—are often associated with giant molecular clouds. They often appear clumpy and filamentary, sometimes showing intricate shapes such as the Horsehead Nebula. H II regio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wind-blown Bubble
A stellar-wind bubble is a cavity light-years across filled with hot gas blown into the interstellar medium by the high-velocity (several thousand km/s) stellar wind from a single massive star of type O or B. Weaker stellar winds also blow bubble structures, which are also called astrospheres. The heliosphere blown by the solar wind, within which all the major planets of the Solar System are embedded, is a small example of a stellar-wind bubble. Stellar-wind bubbles have a two-shock structure. The freely-expanding stellar wind hits an inner termination shock, where its kinetic energy is thermalized, producing 106 K, X-ray-emitting plasma. The hot, high-pressure, shocked wind expands, driving a shock into the surrounding interstellar gas. If the surrounding gas is dense enough (number densities n > 0.1 \mbox^ or so), the swept-up gas radiatively cools far faster than the hot interior, forming a thin, relatively dense shell around the hot, shocked wind. See also *Wolf–R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NGC 6888
The Crescent Nebula (also known as NGC 6888, Caldwell 27, Sharpless 105) is an emission nebula in the constellation Cygnus, about 5000 light-years away from Earth. It was discovered by William Herschel in 1792. It is formed by the fast stellar wind from the Wolf-Rayet star WR 136 (HD 192163) colliding with and energizing the slower moving wind ejected by the star when it became a red giant around 250,000 to 400,000 years ago. The result of the collision is a shell and two shock waves, one moving outward and one moving inward. The inward moving shock wave heats the stellar wind to X-ray-emitting temperatures. It is a rather faint object located about 2 degrees SW of Sadr. For most telescopes it requires a UHC or OIII filter to see. Under favorable circumstances a telescope as small as 8 cm (with filter) can see its nebulosity. Larger telescopes (20 cm or more) reveal the crescent or a Euro The euro ( symbol: €; code: EUR) is the official currency of 19 o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NGC 2359
NGC 2359 (also known as Thor's Helmet) is an emission nebulaSEDS: NGC 2359 in the constellation . The nebula is approximately 3,670 s (11.96 thousand light years) away and 30 light-years in size. The central star is the Wolf-Rayet star WR7, an extremely hot star thought to be in a brief pre- stage ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
WR 104
WR 104 is a triple star system located about from Earth. The primary star is a Wolf–Rayet star (abbreviated as WR), which has a B0.5 main sequence star in close orbit and another more distant fainter companion. The WR star is surrounded by a distinctive spiral Wolf–Rayet nebula, often referred to as a pinwheel nebula. The rotational axis of the binary system, and likely of the two closest stars, is directed approximately towards Earth. Within the next few hundred thousand years, the Wolf–Rayet star is predicted to experience a core-collapse supernova with a small chance of producing a long-duration gamma-ray burst. The possibility of a supernova explosion from WR 104 having destructive consequences for life on Earth stirred interest in the mass media, and several popular science articles have been issued in the press since 2008. Some articles decide to reject the catastrophic scenario, while others leave it as an open question. System The Wolf–Rayet star tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pinwheel Nebula
A pinwheel nebula is a ''nebulous region'' in the shape of a pinwheel. Spiral galaxies The term 'Pinwheel nebula' is an antiquated misnomer used by observers before Edwin Hubble realized that many of these spiral shaped nebulae were actually 'island universes' or what we now call galaxies. Wolf–Rayet nebulae Some Wolf–Rayet stars are surrounded by pinwheel nebulae. These nebulae are formed from the dust that is spewed out of a binary star system. The stellar winds of the two stars collide and form two dust lanes that spiral outward with the rotation of the system. An example of this is WR 104 WR 104 is a triple star system located about from Earth. The primary star is a Wolf–Rayet star (abbreviated as WR), which has a B0.5 main sequence star in close orbit and another more distant fainter companion. The WR star is surr .... External links"The Twisted Tale of Wolf-Rayet 104, First of the Pinwheel Nebulae"Some Wolf–Rayet stars in binaries are close enough ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wolf–Rayet Nebulae , which surrounds a Wolf–Rayet star
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Wolf–Rayet (WR) can mean: * Wolf–Rayet star, a type of evolved, massive star * Wolf–Rayet galaxy, which contains large numbers of Wolf–Rayet stars * Wolf–Rayet nebula A Wolf–Rayet nebula is a nebula which surrounds a Wolf–Rayet star. WR nebulae have been classified in various ways. One of the earliest was by the nature and origin of the nebula: * HII regions * ejecta-type nebulae * wind-blown bubbles Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
