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Wolf–Rayet Nebula
A Wolf-Rayet nebula is a type of nebula created from stellar winds expelled by Wolf-Rayet stars. Wolf-Rayet stars are very hot, highly luminous, and rapidly evolving massive stars that are fusing helium or heavier elements in their cores. Characteristics The strong, dense stellar winds from Wolf-Rayet stars consist of streams of charged particles traveling at speeds of thousands of kilometers per second. These winds slam into the surrounding interstellar medium, generating shock waves that heat and ionize the gas and dust, causing it to glow and emit radiation in visible and other wavelengths In physics and mathematics, wavelength or spatial period of a wave or periodic function is the distance over which the wave's shape repeats. In other words, it is the distance between consecutive corresponding points of the same '' phase'' on .... This process creates an enveloping nebula around the Wolf-Rayet star with a distinctive multi-ring structure. The nebula contains shells ... [...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 i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LHA 115 - N 76A - Eso0310a
LHA may refer to: *Flughafen Lahr (IATA code) * Lha (Cyrillic), a letter of Cyrillic alphabet * Lha (Tibetan), one of the eight classes of gods and demons in Tibetan Buddhism * LHA (file format), a freeware compression utility and associated file format * LHA (for eading Helicopter Academies, "Raising flying standards in Europe" * A US Navy hull classification symbol: Landing helicopter assault (LHA) * LHA, the local hour angle of an astronomical object * Lha Charitable Trust, an Indian nonprofit organization primarily focused on Tibetian social work * 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. * Lincoln Highway Association * Livonia Hockey Association, amateur hockey league in Livonia, Michigan * Local Housing Allowance, welfare benefit in the UK to help tenants with low incomes pay their rent * Stock ticker for Lufthansa Deut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nebula
A nebula (; 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 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 surrounding them, most nebulae are far less dens ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellar Wind
A stellar wind is a flow of gas ejected from the stellar atmosphere, 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. Different stellar classification, types of stars have different types of stellar winds. Post-main sequence, main-sequence stars nearing the ends of their lives often eject large quantities of mass in massive ( \scriptstyle \dot > 10^ solar masses per year), slow (v = 10 km/s) winds. These include red giants and Red supergiant, supergiants, and asymptotic giant branch stars. These winds are understood to be driven by radiation pressure on Cosmic dust, dust condensing in the upper atmosphere of the stars. Young T Tauri stars often have very powerful stellar winds. Massive stars of stellar classification, types O star, O and B V star, B have stellar winds with lower mass loss rates (\scriptstyle \dot 1–2000 km ... [...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 spectroscopy, spectra showing prominent broad emission lines of ionised helium and highly ionised nitrogen or carbon. The spectra indicate very high surface enhancement of Stellar nucleosynthesis, heavy elements, depletion of hydrogen, and strong stellar winds. The Effective temperature, surface temperatures of known Wolf–Rayet stars range from 20,000 Kelvin (unit), K to around 210,000 Kelvin (unit), K, hotter than almost all other kinds of stars. They were previously called W-type stars referring to their Stellar classification, spectral classification. Classic (or population I) Wolf–Rayet stars are Stellar evolution, evolved, massive stars that have completely lost their outer hydrogen and are nuclear fusion, 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; the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luminosity
Luminosity is an absolute measure of radiated electromagnetic radiation, electromagnetic energy per unit time, and is synonymous with the radiant power emitted by a light-emitting object. In astronomy, luminosity is the total amount of electromagnetic energy emitted per unit of time by a star, galaxy, or other astronomical object, astronomical objects. In SI units, luminosity is measured in joules per second, or watts. In astronomy, values for luminosity are often given in the terms of the Solar luminosity, luminosity of the Sun, ''L''⊙. Luminosity can also be given in terms of the astronomical Magnitude (astronomy), magnitude system: the Absolute magnitude#Bolometric magnitude, absolute bolometric magnitude (''M''bol) of an object is a logarithmic measure of its total energy emission rate, while absolute magnitude is a logarithmic measure of the luminosity within some specific wavelength range or Passband, filter band. In contrast, the term ''brightness'' in astronomy is gene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helium
Helium (from ) is a chemical element; it has chemical symbol, symbol He and atomic number 2. It is a colorless, odorless, non-toxic, inert gas, inert, monatomic gas and the first in the noble gas group in the periodic table. Its boiling point is the lowest among all the Chemical element, elements, and it does not have a melting point at standard pressures. It is the second-lightest and second-most Abundance of the chemical elements, abundant element in the observable universe, after hydrogen. It is present at about 24% of the total elemental mass, which is more than 12 times the mass of all the heavier elements combined. Its abundance is similar to this in both the Sun and Jupiter, because of the very high nuclear binding energy (per nucleon) of helium-4 with respect to the next three elements after helium. This helium-4 binding energy also accounts for why it is a product of both nuclear fusion and radioactive decay. The most common isotope of helium in the universe is helium-4, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Visible Spectrum
The visible spectrum is the spectral band, band of the electromagnetic spectrum that is visual perception, visible to the human eye. Electromagnetic radiation in this range of wavelengths is called ''visible light'' (or simply light). The optical spectrum is sometimes considered to be the same as the visible spectrum, but some authors define the term more broadly, to include the ultraviolet and infrared parts of the electromagnetic spectrum as well, known collectively as ''optical radiation''. A typical human eye will respond to wavelengths from about 380 to about 750 nanometers. In terms of frequency, this corresponds to a band in the vicinity of 400–790 Terahertz (unit), terahertz. These boundaries are not sharply defined and may vary per individual. Under optimal conditions, these limits of human perception can extend to 310 nm (ultraviolet) and 1100 nm (near infrared). The spectrum does not contain all the colors that the human visual system can distinguish. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wavelength
In physics and mathematics, wavelength or spatial period of a wave or periodic function is the distance over which the wave's shape repeats. In other words, it is the distance between consecutive corresponding points of the same ''phase (waves), phase'' on the wave, such as two adjacent crests, troughs, or zero crossings. Wavelength is a characteristic of both traveling waves and standing waves, as well as other spatial wave patterns. The multiplicative inverse, inverse of the wavelength is called the ''spatial frequency''. Wavelength is commonly designated by the Greek letter lambda (''λ''). For a modulated wave, ''wavelength'' may refer to the carrier wavelength of the signal. The term ''wavelength'' may also apply to the repeating envelope (mathematics), envelope of modulated waves or waves formed by Interference (wave propagation), interference of several sinusoids. Assuming a sinusoidal wave moving at a fixed phase velocity, wave speed, wavelength is inversely proportion ... [...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. Visibility The Crescent Nebula is a rather small object located about 2 degrees Southwest of Sadr. While considered bright by astronomical imaging standards, visually it is relatively faint. 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&n ... [...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- supernova
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M1-67
M1-67 is an ejecta nebula that surrounds the Wolf–Rayet star WR 124, which is about 6.4 kpc from Earth in the constellation of Sagitta. It contains dust which is caught up in WR 124's solar wind and which absorbs much of the star's light. It was discovered by American astronomer Paul W. Merrill in 1938, at the same time that he discovered the star it surrounds. It is approximately 6 light years across, making it about 20,000 years old. Distance and characteristics A 2010 study focused on M1-67, measuring its expansion rate by using Hubble Space Telescope photographs taken 11 years apart. The expansion rate was then compared to the expansion velocity, which was calculated from the Doppler shift of its nebular emission lines, resulting in a geometric distance of d=3.35 ± 0.67kpc. NASA has confirmed that the released gas is traveling at up to 100,000 mp/h, causing turbulence, and carrying along approximately 100 billion-mile wide glowing blobs, with each blob being around 30 tim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
