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3C 48
3C48 is a quasar discovered in 1960; it was the second source conclusively identified as such. 3C48 was the first source in the Third Cambridge Catalogue of Radio Sources for which an optical identification was found by Allan Sandage and Thomas A. Matthews in 1960 through interferometry. In 1963 Jesse L. Greenstein and Thomas Matthews found that it had a redshift of 0.367, making it one of the highest redshift sources then known. It was not until 1982 that the surrounding faint galactic "nebulosity" was confirmed to have the same redshift as 3C48, cementing its identification as an object in a distant galaxy. This was also the first solid identification of a quasar with a surrounding galaxy at the same redshift. 3C 48 is one of four primary calibrators used by the Very Large Array (along with 3C 138 and 3C 147, and 3C 286). Visibilities of all other sources are calibrated using observed visibilities of one of these four calibrators. Nomenclature The name of the object “ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Third Cambridge Catalogue Of Radio Sources
The Third Cambridge Catalogue of Radio Sources (3C) is an astronomical catalogue of celestial radio sources detected originally at 159 MHz, and subsequently at 178 MHz. History 3C The catalogue was published in 1959 by members of the Cavendish Astrophysics Group, Radio Astronomy Group of the University of Cambridge. Entries in the catalogue are identified by the prefix "3C" followed by the entry number, with a space - for example, 3C 273. The number denotes objects in order of increasing right ascension. The catalogue was produced using the Cambridge Interferometer on the west side of Cambridge. The interferometer had previously been used for the Second Cambridge Catalogue of Radio Sources (2C) survey, published in 1955. 3CR The catalogue was subsequently revised by Bennett in 1962 using observations at 178 MHz, and for many years '3CR' was considered as the definitive listing of the brighter radio sources in the Northern Hemisphere. The revision resulted in a num ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jesse L
Jesse may refer to: People * Jesse (biblical figure), father of David in the Bible * Jesse (given name), including a list of people * Jesse (surname), a list of people Music * ''Jesse'' (album), a 2003 album by Jesse Powell * "Jesse" (song), a 1980 song by Carly Simon * "Jesse", a 1973 song by Janis Ian from the 1974 album ''Stars'', also covered by Roberta Flack on ''Killing Me Softly'' and by Joan Baez * "Jesse", a song from the album '' Valotte'' by Julian Lennon * "Jesse", a song from the album ''The People Tree'' by Mother Earth * "Jesse", a song from the album '' The Drift'' by Scott Walker * "Jesse", a song from the album '' If I Were Your Woman'' by Stephanie Mills * "Jesse", a song from the album ''Donda 2'' by Kanye West Other * ''Jesse'' (film), a 1988 American television film * ''Jesse'' (TV series), a sitcom starring Christina Applegate * ''Jesse'' (novel), a 1994 novel by Gary Soto * ''Jesse'' (picture book), a 1988 children's book by Tim Winton * Je ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nova
A nova ( novae or novas) is a transient astronomical event that causes the sudden appearance of a bright, apparently "new" star (hence the name "nova", Latin for "new") that slowly fades over weeks or months. All observed novae involve white dwarfs in close binary systems, but causes of the dramatic appearance of a nova vary, depending on the circumstances of the two progenitor stars. The main sub-classes of novae are classical novae, recurrent novae (RNe), and dwarf novae. They are all considered to be cataclysmic variable stars. Classical nova eruptions are the most common type. This type is usually created in a close binary star system consisting of a white dwarf and either a main sequence, subgiant, or red giant star. If the orbital period of the system is a few days or less, the white dwarf is close enough to its companion star to draw accreted matter onto its surface, creating a dense but shallow atmosphere. This atmosphere, mostly consisting of hydrogen, is heated by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
White Dwarf
A white dwarf is a Compact star, stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very density, dense: in an Earth sized volume, it packs a mass that is comparable to the Sun. No nuclear fusion takes place in a white dwarf; what light it radiates is from its residual heat. The nearest known white dwarf is Sirius B, at 8.6 light years, the smaller component of the Sirius binary star. There are currently thought to be eight white dwarfs among the hundred star systems nearest the Sun. The unusual faintness of white dwarfs was first recognized in 1910. The name ''white dwarf'' was coined by Willem Jacob Luyten in 1922. White dwarfs are thought to be the final stellar evolution, evolutionary state of stars whose mass is not high enough to become a neutron star or black hole. This includes over 97% of the stars in the Milky Way. After the hydrogen-stellar nucleosynthesis, fusing period of a main sequence, main-sequence star of Stellar mass, lo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Color Index
In astronomy, the color index is a simple numerical expression that determines the color of an object, which in the case of a star gives its temperature. The lower the color index, the more blue (or hotter) the object is. Conversely, the larger the color index, the more red (or cooler) the object is. This is a consequence of the logarithmic magnitude scale, in which brighter objects have smaller (more negative) magnitudes than dimmer ones. For comparison, the whitish Sun has a B−V index of , whereas the bluish Rigel has a B−V of −0.03 (its B magnitude is 0.09 and its V magnitude is 0.12, B−V = −0.03). Traditionally, the color index uses Vega as a zero point. The blue supergiant Theta Muscae has one of the lowest B−V indices at −0.41, while the red giant and carbon star R Leporis has one of the largest, at +5.74. To measure the index, one observes the magnitude of an object successively through two different filters, such as U and B, or B and V, where U is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emission Spectrum
The emission spectrum of a chemical element or chemical compound is the Spectrum (physical sciences), spectrum of frequencies of electromagnetic radiation emitted due to electrons making a atomic electron transition, transition from a high energy state to a lower energy state. The photon energy of the emitted photons is equal to the energy difference between the two states. There are many possible electron transitions for each atom, and each transition has a specific energy difference. This collection of different transitions, leading to different radiated wavelengths, make up an emission spectrum. Each element's emission spectrum is unique. Therefore, spectroscopy can be used to identify elements in matter of unknown composition. Similarly, the emission spectra of molecules can be used in chemical analysis of substances. Emission In physics, emission is the process by which a higher energy quantum mechanical state of a particle becomes converted to a lower one through the emis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectrum
A spectrum (: spectra or spectrums) is a set of related ideas, objects, or properties whose features overlap such that they blend to form a continuum. The word ''spectrum'' was first used scientifically in optics to describe the rainbow of colors in visible light after passing through a prism. In the optical spectrum, light wavelength is viewed as continuous, and spectral colors are seen to blend into one another smoothly when organized in order of their corresponding wavelengths. As scientific understanding of light advanced, the term came to apply to the entire electromagnetic spectrum, including radiation not visible to the human eye. ''Spectrum'' has since been applied by analogy to topics outside optics. Thus, one might talk about the " spectrum of political opinion", or the "spectrum of activity" of a drug, or the " autism spectrum". In these uses, values within a spectrum may not be associated with precisely quantifiable numbers or definitions. Such uses imply a bro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IOP Publishing
IOP Publishing (previously Institute of Physics Publishing) is the publishing company of the Institute of Physics. It provides publications through which scientific research is distributed worldwide, including journals, community websites, magazines, conference proceedings and books. The Institute of Physics is a scientific charity devoted to increasing the practice, understanding and application of physics. Any financial surplus earned by IOP Publishing goes to support physics through the activities of the Institute. The main IOP Publishing headquarters is located in Bristol, England, and the North American headquarters is in Philadelphia, United States. It also has regional offices in Mexico City, Beijing, Tokyo, and Sydney. It employs over 500 staff. It was the first physics publisher to publish a journal on the internet. In 1994, the journal '' Classical and Quantum Gravity'' was published as a TeX file. In January 1996 the organization launched the full electronic journals ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Right Ascension
Right ascension (abbreviated RA; symbol ) is the angular distance of a particular point measured eastward along the celestial equator from the Sun at the equinox (celestial coordinates), March equinox to the (hour circle of the) point in question above the Earth. When paired with declination, these celestial coordinate system, astronomical coordinates specify the location of a point on the celestial sphere in the equatorial coordinate system. An old term, ''right ascension'' (), "''Ascensio recta'' Solis, stellæ, aut alterius cujusdam signi, est gradus æquatorus cum quo simul exoritur in sphæra recta"; roughly translated, "''Right ascension'' of the Sun, stars, or any other sign, is the degree of the equator that rises together in a right sphere" refers to the ''ascension'', or the point on the celestial equator that rises with any celestial object as seen from Earth's equator, where the celestial equator perpendicular, intersects the horizon at a right angle. It contrasts wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Radio Astronomy Observatory
The National Radio Astronomy Observatory (NRAO) is a federally funded research and development center of the United States National Science Foundation operated under cooperative agreement by Associated Universities, Inc. for the purpose of radio astronomy. NRAO designs, builds, and operates its own high-sensitivity radio telescopes for use by scientists around the world. Locations Charlottesville, Virginia The NRAO headquarters is located on the campus of the University of Virginia in Charlottesville, Virginia. The North American ALMA Science Center and the NRAO Technology Center and Central Development Laboratory are also in Charlottesville. Green Bank, West Virginia NRAO was, until October 2016, the operator of the world's largest fully steerable radio telescope, the Robert C. Byrd Green Bank Telescope, which stands near Green Bank, West Virginia. The observatory contains several other telescopes, among them the telescope that utilizes an equatorial mount uncommon for ra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
3C 286
3C 286, also known by its position as 1328+307 ( B1950 coordinates) or 1331+305 (J2000 coordinates), is a quasar at redshift 0.8493 with a radial velocity of 164,137 km/s. It is part of the Third Cambridge Catalogue of Radio Sources (3C Survey). The 3C Survey was conducted at the relatively low radio frequencies of 159 and 178 MHz. The total power measurements were made with an instrument that produced a 4.6 degree by 13.6 arc minute fan-beam, and interferometric measurements were made with a synthesized beam width of about 7.5 arc minutes. Those beams were too broad to produce coordinates precise enough to allow the radio source to be matched with a corresponding faint optical counterpart. In 1962, 3C 286 was observed with the higher frequency two-element interferometer at Owens Valley Radio Observatory, which produced improved source coordinates with a precision of ~10 arc seconds. With the new coordinates, observations at the Palomar Observatory allowed the optical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
3C 147
3C 147 (B0538+498) is a compact steep-spectrum (CSS) quasar that was discovered in 1964. It is located in the constellation Auriga not far in the sky from the 5th magnitude star Omicron Aurigae. The "distance" of a far away galaxy depends on the distance measurement used. With a redshift of 0.545, light from this active galaxy is estimated to have taken around 5.1 billion years to reach Earth. But as a result of the expansion of the Universe, the present (co-moving) distance to this galaxy is about 6.4 billion light-years (1974 M pc). Very Long Baseline Array (VLBA) observations have identified a complex central region that is dominated by two bright components, A and B. The separation between the two central components of the source seems to be increasing with an apparent velocity ( superluminal motion) of 1.2 ± 0.4 c. 3C 147 is one of four primary calibrators used by the Very Large Array (along with 3C 48, 3C 138 3C 138 is a quasar located in the constellation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
