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Cygnus A
Cygnus A
Cygnus A
(3C 405) is a radio galaxy, and one of the strongest radio sources in the sky. It was discovered by Grote Reber
Grote Reber
in 1939. In 1951, Cygnus A, along with Cassiopeia A, and Puppis A
Puppis A
were the first "radio stars" identified with an optical source. Of these, Cygnus A
Cygnus A
became the first radio galaxy; the other two being nebulae inside the Milky Way.[4] In 1953 Roger Jennison and M K Das Gupta showed it to be a double source.[5] Like all radio galaxies, it contains an active galactic nucleus. The super massive black hole at the core has a mass of 7039497137500000000♠(2.5±0.7)×109 M☉.[3] Images of the galaxy in the radio portion of the electromagnetic spectrum show two jets protruding in opposite directions from the galaxy's center
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J2000
In astronomy, an epoch is a moment in time used as a reference point for some time-varying astronomical quantity, such as the celestial coordinates or elliptical orbital elements of a celestial body, because these are subject to perturbations and vary with time.[1] These time-varying astronomical quantities might include, for example, the mean longitude or mean anomaly of a body, the node of its orbit relative to a reference plane, the direction of the apogee or aphelion of its orbit, or the size of the major axis of its orbit. The main use of astronomical quantities specified in this way is to calculate other relevant parameters of motion, in order to predict future positions and velocities
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Transient Astronomical Event
A transient astronomical event, often shortened by astronomers to a transient, is an astronomical object or phenomenon whose duration may be from seconds to days, weeks, or even several years. This is in contrast to the timescale of the millions or billions of years during which the galaxies and their component stars in our universe have evolved. Singularly, the term is used for violent deep sky events such as supernovae, hypernovae, quark-nova, gamma ray bursts, transits, eclipses, gravitational microlensing,[1] and tidal disruption events, etc. These events are part of the broader topic of time domain astronomy.Contents1 History 2 See also 3 References 4 Further reading 5 External links 6 See alsoHistory[edit] Before the invention of telescopes, events such as these that were visible to the naked eye, from within or near the Milky Way Galaxy, were very rare, and sometimes hundreds of years apart
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Radio Galaxy
Radio
Radio
galaxies and their relatives, radio-loud quasars and blazars, are types of active galaxy that are very luminous at radio wavelengths, with luminosities up to 1039 W between 10 MHz and 100 GHz.[1] The radio emission is due to the synchrotron process. The observed structure in radio emission is determined by the interaction between twin jets and the external medium, modified by the effects of relativistic beaming. The host galaxies are almost exclusively large elliptical galaxies. Radio-loud active galaxies can be detected at large distances, making them valuable tools for observational cosmology
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Puppis A
Puppis A (Pup A) is a supernova remnant (SNR) about 100 lightyears in diameter and roughly 6500–7000 lightyears distant.[1] Its apparent angular diameter is about 1 degree.[2] The light of the supernova explosion reached Earth approximately 3700 years ago. Although it overlaps the Vela Supernova Remnant, it is four times more distant. A hypervelocity neutron star known as the Cosmic Cannonball has been found in this SNR.Contents1 Puppis X-1 2 Gallery 3 References 4 See alsoPuppis X-1[edit] Puppis X-1 (Puppis A) was discovered by a Skylark flight in October 1971, viewed for 1 min with an accuracy ≥ 2 arcsec,[3] probably at 1M 0821-426, with Puppis A (RA 08h 23m 08.16s Dec -42° 41′ 41.40″) as the likely visual counterpart. Puppis A is one of the brightest X-ray sources in the X-ray sky
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Super Massive Black Hole
A supermassive black hole (SMBH or SBH) is the largest type of black hole, on the order of hundreds of thousands to billions of solar masses (M☉), and is found in the centre of almost all currently known massive galaxies.[1][2] In the case of the Milky Way, the SMBH corresponds with the location of Sagittarius A*.[3][4]Contents1 Description 2 History of research 3 Formation 4 Doppler measurements 5 In the Milky Way 6 Outside the Milky Way 7 In fiction 8 See also 9 References 10 Further reading 11 External linksDescription[edit] Supermassive black holes have properties that distinguish them from lower-mass classifications. First, the average density of a SMBH (defined as the mass of the black hole divided by the volume within its Schwarzschild radius) can be less than the density of water in the case of some SMBHs.[5] This is because the Schwarzschild radius is directly proportional to mass, while density is inversely proportional to the volume
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Solar Mass
The solar mass (M☉) is a standard unit of mass in astronomy, equal to approximately 7030200000000000000♠2×1030 kg. It is used to indicate the masses of other stars, as well as clusters, nebulae and galaxies
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Radio Waves
Radio waves
Radio waves
are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies as high as 300  GHz to as low as 3 kHz, though some definitions[1][2] describe waves above 300 MHz or 3  GHz as microwaves, or include waves of any lower frequency. At 300 GHz, the corresponding wavelength is 1 mm (0.039 in), and at 3 kHz is 100 km (62 mi). Like all other electromagnetic waves, they travel at the speed of light. Naturally occurring radio waves are generated by lightning, or by astronomical objects. Artificially generated radio waves are used for fixed and mobile radio communication, broadcasting, radar and other navigation systems, communications satellites, computer networks and many other applications
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Electromagnetic Spectrum
The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energies. The electromagnetic spectrum covers electromagnetic waves with frequencies ranging from below one hertz to above 1025 hertz, corresponding to wavelengths from thousands of kilometers down to a fraction of the size of an atomic nucleus. This frequency range is divided into separate bands, and the electromagnetic waves within each frequency band are called by different names; beginning at the low frequency (long wavelength) end of the spectrum these are: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays at the high-frequency (short wavelength) end. The electromagnetic waves in each of these bands have different characteristics, such as how they are produced, how they interact with matter, and their practical applications
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Visible Spectrum
The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation
Electromagnetic radiation
in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 390 to 700 nm.[1] In terms of frequency, this corresponds to a band in the vicinity of 430–770 THz. The spectrum does not, however, contain all the colors that the human eyes and brain can distinguish. Unsaturated colors such as pink, or purple variations such as magenta, are absent, for example, because they can be made only by a mix of multiple wavelengths. Colors containing only one wavelength are also called pure colors or spectral colors. Visible wavelengths pass through the "optical window", the region of the electromagnetic spectrum that allows wavelengths to pass largely unattenuated through the Earth's atmosphere
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Intergalactic Space
Outer space, or just space, is the expanse that exists beyond the Earth
Earth
and between celestial bodies. Outer space
Outer space
is not completely empty—it is a hard vacuum containing a low density of particles, predominantly a plasma of hydrogen and helium as well as electromagnetic radiation, magnetic fields, neutrinos, dust, and cosmic rays
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Flux Density
Flux
Flux
describes the quantity which passes through a surface or substance. A flux is either a concept based in physics or used with applied mathematics. Both concepts have mathematical rigor, enabling comparison of the underlying math when the terminology is unclear. For transport phenomena, flux is a vector quantity, describing the magnitude and direction of the flow of a substance or property
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Galaxy
A galaxy is a gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter.[1][2] The word galaxy is derived from the Greek galaxias (γαλαξίας), literally "milky", a reference to the Milky Way. Galaxies range in size from dwarfs with just a few hundred million (108) stars to giants with one hundred trillion (1014) stars,[3] each orbiting its galaxy's center of mass. Galaxies are categorized according to their visual morphology as elliptical,[4] spiral, or irregular.[5] Many galaxies are thought to have black holes at their active centers
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Supernova
A supernova (/ˌsuːpərnoʊvə/ plural: supernovae /ˌsuːpərnoʊviː/ or supernovas, abbreviations: SN and SNe) is a transient astronomical event that occurs during the last stellar evolutionary stages of a massive star's life, whose destruction is marked by one final titanic explosion. This causes the sudden appearance of a "new" bright star, before slowly fading from sight over several weeks or months. SN 1994D
SN 1994D
(bright spot on the lower left), a Type Ia supernova outshining its home galaxy, NGC 4526Supernovae are more energetic than novae. In Latin, nova means "new", referring astronomically to what appears to be a temporary new bright star. Adding the prefix "super-" distinguishes supernovae from ordinary novae, which are far less luminous
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Binary Black Hole
A binary black hole (BBH) is a system consisting of two black holes in close orbit around each other. Like black holes themselves, binary black holes are often divided into stellar binary black holes, formed either as remnants of high-mass binary star systems or by dynamic processes and mutual capture, and binary supermassive black holes believed to be a result of galactic mergers. For many years, proving the existence of BBHs was made difficult because of the nature of black holes themselves, and the limited means of detection available. However, in the event that a pair of black holes were to merge, an immense amount of energy should be given off as gravitational waves, with distinctive waveforms that can be calculated using general relativity.[2][3][4] Therefore, during the late 20th and early 21st century, BBHs became of great interest scientifically as a potential source of such waves, and a means by which gravitational waves could be proven to exist
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SIMBAD
SIMBAD
SIMBAD
(the Set of Identifications, Measurements, and Bibliography for Astronomical Data) is an astronomical database of objects beyond the Solar System. It is maintained by the Centre de données astronomiques de Strasbourg (CDS), France. SIMBAD
SIMBAD
was created by merging the Catalog of Stellar Identifications (CSI) and the Bibliographic Star Index as they existed at the Meudon Computer Centre until 1979, and then expanded by additional source data from other catalogues and the academic literature. The first on-line interactive version, known as Version 2, was made available in 1981. Version 3, developed in the C language and running on UNIX stations at the Strasbourg Observatory, was released in 1990
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