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Evaporating Gaseous Globule
An evaporating gas globule or EGG is a region of hydrogen gas in outer space approximately 100 astronomical units in size, such that gases shaded by it are shielded from ionizing UV rays. Dense areas of gas shielded by an evaporating gas globule can be conducive to the birth of stars. Evaporating gas globules were first conclusively identified via photographs of the Pillars of Creation in the Eagle Nebula taken by the Hubble Space Telescope in 1995. EGG's are the likely predecessors of new protostars. Inside an EGG the gas and dust are denser than in the surrounding dust cloud. Gravity pulls the cloud even more tightly together as the EGG continues to draw in material from its surroundings. As the cloud density builds up the globule becomes hotter under the weight of the outer layers, a protostar is formed inside the EGG. A protostar may have too little mass to become a star. If so it becomes a brown dwarf. If the protostar has sufficient mass, the density reaches a critical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pillars Of Creation
''Pillars of Creation'' is a photograph taken by the Hubble Space Telescope of elephant trunks of interstellar gas and dust in the Eagle Nebula, in the Serpens constellation, some from Earth. These elephant trunks had been discovered by John Charles Duncan in 1920 on a plate made with the Mount Wilson Observatory 60-inch telescope. They are named so because the gas and dust are in the process of creating new stars, while also being eroded by the light from nearby stars that have recently formed.Embryonic Stars Emerge from Interstellar "Eggs" Hubble news release Taken on April 1, 1995, it was named one of the top ten photographs from Hubble by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eagle Nebula
The Eagle Nebula (catalogued as Messier 16 or M16, and as NGC 6611, and also known as the Star Queen Nebula) is a young open cluster of stars in the constellation Serpens, discovered by Jean-Philippe de Cheseaux in 1745–46. Both the "Eagle" and the "Star Queen" refer to visual impressions of the dark silhouette near the center of the nebula, an area made famous as the "Pillars of Creation" imaged by the Hubble Space Telescope. The nebula contains several active star-forming gas and dust regions, including the aforementioned Pillars of Creation. The Eagle Nebula lies in the Sagittarius Arm of the Milky Way. Characteristics The Eagle Nebula is part of a diffuse emission nebula, or H II region, which is catalogued as IC 4703. This region of active current star formation is about 5700 light-years distant. A spire of gas that can be seen coming off the nebula in the northeastern part is approximately 9.5 light-years or about 90 trillion kilometers long. The cluster associated wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomical Units
The astronomical unit (symbol: au, or or AU) is a unit of length, roughly the distance from Earth to the Sun and approximately equal to or 8.3 light-minutes. The actual distance from Earth to the Sun varies by about 3% as Earth orbits the Sun, from a maximum (aphelion) to a minimum (perihelion) and back again once each year. The astronomical unit was originally conceived as the average of Earth's aphelion and perihelion; however, since 2012 it has been defined as exactly (see below for several conversions). The astronomical unit is used primarily for measuring distances within the Solar System or around other stars. It is also a fundamental component in the definition of another unit of astronomical length, the parsec. History of symbol usage A variety of unit symbols and abbreviations have been in use for the astronomical unit. In a 1976 resolution, the International Astronomical Union (IAU) had used the symbol ''A'' to denote a length equal to the astronomical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
UV Rays
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight, and constitutes about 10% of the total electromagnetic radiation output from the Sun. It is also produced by electric arcs and specialized lights, such as mercury-vapor lamps, tanning lamps, and black lights. Although long-wavelength ultraviolet is not considered an ionizing radiation because its photons lack the energy to ionize atoms, it can cause chemical reactions and causes many substances to glow or fluoresce. Consequently, the chemical and biological effects of UV are greater than simple heating effects, and many practical applications of UV radiation derive from its interactions with organic molecules. Short-wave ultraviolet light damages DNA and sterilizes surfaces with which it comes into contact. For hum ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hubble Space Telescope
The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versatile, renowned both as a vital research tool and as a public relations boon for astronomy. The Hubble telescope is named after astronomer Edwin Hubble and is one of NASA's Great Observatories. The Space Telescope Science Institute (STScI) selects Hubble's targets and processes the resulting data, while the Goddard Space Flight Center (GSFC) controls the spacecraft. Hubble features a mirror, and its five main instruments observe in the ultraviolet, visible, and near-infrared regions of the electromagnetic spectrum. Hubble's orbit outside the distortion of Earth's atmosphere allows it to capture extremely high-resolution images with substantially lower background light than ground-based telescopes. It has recorded some of the most detaile ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protostar
A protostar is a very young star that is still gathering mass from its parent molecular cloud. The protostellar phase is the earliest one in the process of stellar evolution. For a low-mass star (i.e. that of the Sun or lower), it lasts about 500,000 years. The phase begins when a molecular cloud fragment first collapses under the force of self-gravity and an opaque, pressure supported core forms inside the collapsing fragment. It ends when the infalling gas is depleted, leaving a pre-main-sequence star, which contracts to later become a main-sequence star at the onset of hydrogen fusion producing helium. History The modern picture of protostars, summarized above, was first suggested by Chushiro Hayashi in 1966. In the first models, the size of protostars was greatly overestimated. Subsequent numerical calculations clarified the issue, and showed that protostars are only modestly larger than main-sequence stars of the same mass. This basic theoretical result has been confirmed b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brown Dwarf
Brown dwarfs (also called failed stars) are substellar objects that are not massive enough to sustain nuclear fusion of ordinary hydrogen ( 1H) into helium in their cores, unlike a main-sequence star. Instead, they have a mass between the most massive gas giant planets and the least massive stars, approximately 13 to 80 times that of Jupiter (). However, they can fuse deuterium ( 2H), and the most massive ones (> ) can fuse lithium ( 7Li). Astronomers classify self-luminous objects by spectral class, a distinction intimately tied to the surface temperature, and brown dwarfs occupy types M, L, T, and Y. As brown dwarfs do not undergo stable hydrogen fusion, they cool down over time, progressively passing through later spectral types as they age. Despite their name, to the naked eye, brown dwarfs would appear in different colors depending on their temperature. The warmest ones are possibly orange or red, while cooler brown dwarfs would likely appear magenta or black to th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HR Diagram
HR, Hr or hr may refer to: Arts and media Film and television * ''H.R. Pufnstuf'', a children's television series from 1969 * ''HR'', a 2013 television drama starring Alicia Silverstone * HR, a criminal organisation in the American TV series ''Person of Interest'' Other media * HR (girl group), Japan * Hessischer Rundfunk (Hessian Broadcasting), Germany * ''Homestar Runner'', an Internet cartoon * HyperRogue, a roguelike video game Fictional characters * H. R. Wells, a character from ''The Flash'' television series Business and finance * Human resources, personnel * Human resource management * Ukrainian hryvnia, currency Government and politics * Human rights * High Representative of the Union for Foreign Affairs and Security Policy of the European Union * United States House of Representatives Languages * hr (ISO 639-1 code) for the Croatian language * , a two-letter combination used in some languages ** Reduction of /hr/ to /r/ in Old/Middle English People * H.R. (bo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Very Large Telescope
The Very Large Telescope (VLT) is a telescope facility operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of northern Chile. It consists of four individual telescopes, each with a primary mirror 8.2 m across, which are generally used separately but can be used together to achieve very high angular resolution. The four separate optical telescopes are known as ''Antu'', ''Kueyen'', ''Melipal'', and ''Yepun'', which are all words for astronomical objects in the Mapuche language. The telescopes form an array complemented by four movable Auxiliary Telescopes (ATs) of 1.8 m aperture. The VLT operates at visible light, visible and infrared wavelengths. Each individual telescope can detect objects roughly four billion times fainter than can be detected with the naked eye, and when all the telescopes are combined, the facility can achieve an angular resolution of about 0.002 arcsecond. In single telescope mode of operation angular resolution is ab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding the National Advisory Committee for Aeronautics (NACA), to give the U.S. space development effort a distinctly civilian orientation, emphasizing peaceful applications in space science. NASA has since led most American space exploration, including Project Mercury, Project Gemini, the 1968-1972 Apollo Moon landing missions, the Skylab space station, and the Space Shuttle. NASA supports the International Space Station and oversees the development of the Orion spacecraft and the Space Launch System for the crewed lunar Artemis program, Commercial Crew spacecraft, and the planned Lunar Gateway space station. The agency is also responsible for the Launch Services Program, which provides oversight of launch operations and countdown management f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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