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NGC 5882
NGC 5882 is a small planetary nebula in the southern constellation of Lupus, positioned about 1.5° to the southwest of the star Epsilon Lupi. It was discovered by English astronomer John Herschel on July 2, 1834 from the Cape of Good Hope observatory. John L. E. Dreyer described it as "very small, round, quite sharp". It is located at a distance of approximately from the Sun. This nebular region consists of the cast-off outer atmosphere of an aging star. It is roughly elliptical in shape with several clumps of ionized material, and is surrounded by a larger region of low-level emission that extends for three times the nominal diameter of the main nebula. The nebula is expanding with an average velocity of . It consists of two shells: the inner shell is elliptical and measures , while the more rapidly expanding outer shell is rounder with a diameter of . The inner shell has what appears to be multiple bubble-like shapes. The clumps in the outer shell may be the result of insta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NGC 5882 HST
NGC commonly refers to: * New General Catalogue of Nebulae and Clusters of Stars, a catalogue of deep sky objects in astronomy NGC may also refer to: Companies * NGC Corporation, name of US electric company Dynegy, Inc. from 1995 to 1998 * National Gas Company of Trinidad and Tobago, state-owned natural gas company in Trinidad and Tobago * National Grid plc, a former name of National Grid Electricity Transmission plc, the operator of the British electricity transmission system * Northrop Grumman Corporation, aerospace and defense conglomerate formed from the merger of Northrop Corporation and Grumman Corporation in 1994 * Numismatic Guaranty Corporation, coin certification company in the United States Other uses * National Gallery of Canada, art gallery founded in 1880 in Ottawa, Canada * National Geographic, documentary and reality television channel established in the United States in 2001 formerly called National Geographic Channel * Native Girls Code, US non-profit orga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cape Of Good Hope
The Cape of Good Hope ( af, Kaap die Goeie Hoop ) ;''Kaap'' in isolation: pt, Cabo da Boa Esperança is a rocky headland on the Atlantic coast of the Cape Peninsula in South Africa. A common misconception is that the Cape of Good Hope is the southern tip of Africa, based on the misbelief that the Cape was the dividing point between the Atlantic and Indian oceans, and have nothing to do with north or south. In fact, by looking at a map, the southernmost point of Africa is Cape Agulhas about to the east-southeast. The currents of the two oceans meet at the point where the warm-water Agulhas current meets the cold-water Benguela current and turns back on itself. That oceanic meeting point fluctuates between Cape Agulhas and Cape Point (about east of the Cape of Good Hope). When following the western side of the African coastline from the equator, however, the Cape of Good Hope marks the point where a ship begins to travel more eastward than southward. Thus, the first mode ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luminosity Of The Sun
The solar luminosity (), is a unit of radiant flux (power emitted in the form of photons) conventionally used by astronomers to measure the luminosity of stars, galaxies and other celestial objects in terms of the output of the Sun. One nominal solar luminosity is defined by the International Astronomical Union to be . This does not include the solar neutrino luminosity, which would add , or , i.e. a total of (the mean energy of the solar photons is 26 MeV and that of the solar neutrinos 0.59 MeV, i.e. 2.27%; the Sun emits photons and as many neutrinos each second, of which per m2 reach the Earth each second). The Sun is a weakly variable star, and its actual luminosity therefore fluctuates. The major fluctuation is the eleven-year solar cycle (sunspot cycle) that causes a quasi-periodic variation of about ±0.1%. Other variations over the last 200–300 years are thought to be much smaller than this. Determination Solar luminosity is related to solar irradiance (the solar c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apparent Visual Magnitude
Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's light caused by interstellar dust along the line of sight to the observer. The word ''magnitude'' in astronomy, unless stated otherwise, usually refers to a celestial object's apparent magnitude. The magnitude scale dates back to the ancient Roman astronomer Claudius Ptolemy, whose star catalog listed stars from 1st magnitude (brightest) to 6th magnitude (dimmest). The modern scale was mathematically defined in a way to closely match this historical system. The scale is reverse logarithmic: the brighter an object is, the lower its magnitude number. A difference of 1.0 in magnitude corresponds to a brightness ratio of \sqrt /math>, or about 2.512. For example, a star of magnitude 2.0 is 2.512 times as bright as a star of magnitude 3.0, 6.3 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dredge-up
A dredge-up is any one of several stages in the evolution of some stars. By definition, during a ''dredge-up'', a convection zone extends all the way from the star's surface down to the layers of material that have undergone fusion. Consequently, the fusion products are mixed into the outer layers of the star's atmosphere, where they can be seen in stellar spectra. Multiple stages *;''The first dredge-up'': The first dredge-up occurs when a main-sequence star enters the red-giant branch. As a result of the convective mixing, the outer atmosphere will display the spectral signature of hydrogen fusion: The C/ C and C/ N ratios are lowered, and the surface abundances of lithium and beryllium may be reduced. *;''The second dredge-up'': The second dredge-up occurs in stars with 4–8 solar masses. When helium fusion comes to an end at the core, convection mixes the products of the CNO cycle. This second dredge-up causes an increase in the surface abundance of He and N, whereas t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elemental Abundance
The abundance of the chemical elements is a measure of the occurrence of the chemical elements relative to all other elements in a given environment. Abundance is measured in one of three ways: by the mass-fraction (the same as weight fraction); by the mole-fraction (fraction of atoms by numerical count, or sometimes fraction of molecules in gases); or by the volume-fraction. Volume-fraction is a common abundance measure in mixed gases such as planetary atmospheres, and is similar in value to molecular mole-fraction for gas mixtures at relatively low densities and pressures, and ideal gas mixtures. Most abundance values in this article are given as mass-fractions. For example, the abundance of oxygen in pure water can be measured in two ways: the ''mass fraction'' is about 89%, because that is the fraction of water's mass which is oxygen. However, the ''mole-fraction'' is about 33% because only 1 atom of 3 in water, H2O, is oxygen. As another example, looking at the ''mass-fract ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Louis Emil Dreyer
John Louis Emil Dreyer (13 February 1852 – 14 September 1926) was a Danish astronomer who spent most of his career working in Ireland. He spent the last decade of his life in Oxford, England. Life Dreyer was born in Copenhagen. His father, Lieutenant General John Christopher Dreyer, was the Danish Minister for War and the Navy. When he was 14 he became interested in astronomy and regularly visited Hans Schjellerup at the Copenhagen observatory. He was educated in Copenhagen, taking an MA in 1872. While the same university later awarded him a PhD, in 1874. But in 1874, at the age of 22, he went to Parsonstown, Ireland. There he worked as the assistant of Lord Rosse (the son and successor of the Lord Rosse who built the Leviathan of Parsonstown telescope). During 1878 he moved to Dunsink, the site of the Trinity College Observatory of Dublin University to work for Robert Stawell Ball. In 1882 he relocated again, this time to Armagh Observatory, where he served as Director u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Herschel
Sir John Frederick William Herschel, 1st Baronet (; 7 March 1792 – 11 May 1871) was an English polymath active as a mathematician, astronomer, chemist, inventor, experimental photographer who invented the blueprint and did botanical work. Herschel originated the use of the Julian day system in astronomy. He named seven moons of Saturn and four moons of Uranus – the seventh planet, discovered by his father Sir William Herschel. He made many contributions to the science of photography, and investigated colour blindness and the chemical power of ultraviolet rays. His ''Preliminary Discourse'' (1831), which advocated an inductive approach to scientific experiment and theory-building, was an important contribution to the philosophy of science. Early life and work on astronomy Herschel was born in Slough, Buckinghamshire, the son of Mary Baldwin and astronomer William Herschel. He was the nephew of astronomer Caroline Herschel. He studied shortly at Eton College an ... [...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] |
Epsilon Lupi
Epsilon Lupi, Latinized from ε Lup, is a multiple star system in the southern constellation of Lupus. At an apparent visual magnitude of 3.41, Epsilon Lupi can be readily viewed from the southern hemisphere with sufficiently dark skies. It is the fifth-brightest star or star system in the constellation. Parallax measurements give a distance to this system of roughly . This system is what astronomers term a double-lined spectroscopic binary. When the spectrum is examined, the absorption line features of both stars can be viewed. As a result of the Doppler effect, these lines shift back and forth in frequency as the two stars orbit around each other. This allows some of their orbital elements to be deduced, even though the individual stars have not been resolved with a telescope. The pair share a close, elliptical orbit with a period of 4.55970 days. The orbital eccentricity is 0.277, which means that at the separation at closest approach, or periapsis, is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Constellation
A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the earliest constellations likely go back to prehistory. People used them to relate stories of their beliefs, experiences, creation myth, creation, or mythology. Different cultures and countries adopted their own constellations, some of which lasted into the early 20th century before today's constellations were internationally recognized. The recognition of constellations has changed significantly over time. Many changed in size or shape. Some became popular, only to drop into obscurity. Some were limited to a single culture or nation. The 48 traditional Western constellations are Greek. They are given in Aratus' work ''Phenomena'' and Ptolemy's ''Almagest'', though their origin probably predates these works by several centuries. Constellation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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