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Black Hole Binary
A binary black hole (BBH), or black hole binary, is an astronomical object consisting of two black holes in close orbit around each other. Like black holes themselves, binary black holes are often divided into binary stellar 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 binary black holes 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. Therefore, during the late 20th and early 21st century, binary black holes became of great interest scientifically as a potential source of such waves and a means by which gravitational ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BBH Gravitational Lensing Of Gw150914
BBH may refer to: Businesses * Baltic Beverages Holding, now owned by the Carlsberg Group * Bartle Bogle Hegarty, a British advertising agency * Brown Brothers Harriman & Co., an American private investment bank * Bellevue Healthcare Trust, listed on the London Stock Exchange as BBH People * Bruce Barrymore Halpenny, English military historian * Byun Baek-hyun, South Korean singer and actor * BadBoyHalo, a member of the now defunct Dream SMP server * The Darkstalkers character Bbhood#Baby Bonnie Hood, Baby Bonnie Hood Sport * Baseball Heaven, New York, US * Brest Bretagne Handball, a French handball club * Burgos BH, a Spanish cycling team Transport * Brighton Beach railway station, Melbourne * Stralsund–Barth Airport, Germany * Buckeye Bahamas Hub, fuel terminal in The Bahamas See also * BBHS (other) {{disambig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light-year
A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in vacuum in one Julian year (365.25 days). Despite its inclusion of the word "year", the term should not be misinterpreted as a unit of time. The ''light-year'' is most often used when expressing distances to stars and other distances on a galactic scale, especially in non-specialist contexts and popular science publications. The unit most commonly used in professional astronomy is the parsec (symbol: pc, about 3.26 light-years). Definitions As defined by the International Astronomical Union (IAU), the light-year is the product of the Julian year (365.25 days, as opposed to the 365.2425-day Gregorian year or the 365.24219-day Tropical year that both approxim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dynamical Friction
In astrophysics, dynamical friction or Chandrasekhar friction, sometimes called gravitational drag, is loss of momentum and kinetic energy of moving bodies through gravitational interactions with surrounding matter in space. It was first discussed in detail by Subrahmanyan Chandrasekhar in 1943. Intuitive account An intuition for the effect can be obtained by thinking of a massive object moving through a cloud of smaller lighter bodies. The effect of gravity causes the light bodies to accelerate and gain momentum and kinetic energy (see slingshot effect). By conservation of energy and momentum, we may conclude that the heavier body will be slowed by an amount to compensate. Since there is a loss of momentum and kinetic energy for the body under consideration, the effect is called ''dynamical friction''. Another equivalent way of thinking about this process is that as a large object moves through a cloud of smaller objects, the gravitational effect of the larger object pulls ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyperbolic Trajectory
In astrodynamics or celestial mechanics, a hyperbolic trajectory or hyperbolic orbit is the trajectory of any object around a central body with more than enough speed to escape the central object's gravitational pull. The name derives from the fact that according to Newtonian theory such an orbit has the shape of a hyperbola. In more technical terms this can be expressed by the condition that the orbital eccentricity is greater than one. Under simplistic assumptions a body traveling along this trajectory will coast towards infinity, settling to a final excess velocity relative to the central body. Similarly to parabolic trajectories, all hyperbolic trajectories are also escape trajectories. The specific energy of a hyperbolic trajectory orbit is positive. Planetary flybys, used for gravitational slingshots, can be described within the planet's sphere of influence using hyperbolic trajectories. Parameters describing a hyperbolic trajectory Like an elliptical orbit, a hyp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PKS 1302-102
PKS may refer to: * Pammal K. Sambandam, a 2002 Tamil language comedy film * Państwowa Komunikacja Samochodowa, Polish transport organization * Parkstone railway station, station code * Phi Kappa Sigma International Fraternity * Parkes Catalogue of Radio Sources, an astronomical catalogue An astronomical catalogue is a list or tabulation of astronomical objects, typically grouped together because they share a common type, Galaxy morphological classification, morphology, origin, means of detection, or method of discovery. The olde ... * Polyketide synthases, enzymes * Prosperous Justice Party (''Partai Keadilan Sejahtera''), Indonesia * Serbian Chamber of Commerce * Pallister-Killian syndrome, a rare genetic disorder which is caused by additional 4 copies of the short arm of chromosome 12 {{disambig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peculiar Velocity
Peculiar motion or peculiar velocity refers to the velocity of an object relative to a ''rest frame''—usually a frame in which the average velocity of some objects is zero. Galactic astronomy In galactic astronomy, peculiar motion refers to the motion of an object (usually a star) relative to a Galactic rest frame. Local objects are commonly examined as to their vectors of position angle and radial velocity. These can be combined through vector addition to state the object's motion relative to the Sun. Velocities for local objects are sometimes reported with respect to the local standard of rest (LSR)—the average local motion of material in the galaxy—instead of the Sun's rest frame. Translating between the LSR and heliocentric rest frames requires the calculation of the Sun's peculiar velocity in the LSR. Cosmology In physical cosmology, peculiar velocity refers to the components of a galaxy's velocity that deviate from the Hubble flow. According to Hubble's law, gal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OJ287
OJ 287 is a BL Lac object 4 billion light-years from Earth that has produced quasi-periodic optical outbursts going back approximately 120 years, as first apparent on photographic plates from 1891. Seen on photographic plates since at least 1887, it was first detected at radio wavelengths during the course of the Ohio Sky Survey. It is a supermassive black hole binary (SMBHB). The intrinsic brightness of the flashes corresponds to over a trillion times the Sun's luminosity, greater than the entire Milky Way galaxy's light output. Characteristics Given the variability in the SMBHB's bursts and properties, multiple models have been proposed to account for these flashes. The initial model estimates the mass of the primary black hole to be approximately 18.35 billion solar masses and the secondary black hole around 150 million solar masses. More recent models estimate that the central supermassive black hole has a mass of 100 million solar masses, much less than previous estimation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NGC 6240
NGC 6240, also known as the Starfish Galaxy, is a nearby ultraluminous infrared galaxy (ULIRG) in the constellation Ophiuchus. It was discovered by French astronomer Édouard Stephan on 12 July 1871. The galaxy is the remnant of a merger between three smaller galaxies. The collision between the three progenitor galaxies has resulted in a single, larger galaxy with three distinct nuclei and a highly disturbed structure, including faint extensions and loops. Double nuclei Star formation versus supermassive black holes The power sources of ULIRGs in general has been greatly debated. Infrared light from galaxies generally originates from dust in the interstellar medium. ULIRGs are abnormally bright in the infrared. The infrared dust emission in ULIRGs is over one trillion times more luminous than the Sun (i.e. it has an infrared luminosity of ). Astronomers have speculated that either intense star formation regions or active galactic nuclei (which contain supermassive black hol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galaxy Merger
Galaxy mergers can occur when two (or more) Galaxy, galaxies collide. They are the most violent type of Interacting galaxy, galaxy interaction. The Gravitation, gravitational interactions between galaxies and the friction between the gas and Cosmic dust, dust have major effects on the galaxies involved, but the exact effects of such mergers depend on a wide variety of parameters such as collision angles, speeds, and relative size/composition, and are currently an extremely active area of research. Galaxy mergers are important because the merger rate is a fundamental measurement of Galaxy formation and evolution, galaxy evolution and also provides astronomers with clues about how galaxies grew into their current forms over long stretches of time. Description During the merger, stars and dark matter in each galaxy become affected by the approaching galaxy. Toward the late stages of the merger, the Potential energy, gravitational potential begins changing so quickly that star orbits ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gravitational Wave Observation
Gravitational-wave astronomy is a subfield of astronomy concerned with the detection and study of gravitational waves emitted by astrophysical sources. Gravitational waves are minute distortions or ripples in spacetime caused by the acceleration of massive objects. They are produced by cataclysmic events such as the merger of binary black holes, the coalescence of binary neutron stars, supernova explosions and processes including those of the early universe shortly after the Big Bang. Studying them offers a new way to observe the universe, providing valuable insights into the behavior of matter under extreme conditions. Similar to electromagnetic radiation (such as light wave, radio wave, infrared radiation and X-rays) which involves transport of energy via propagation of electromagnetic field fluctuations, gravitational radiation involves fluctuations of the relatively weaker gravitational field. The existence of gravitational waves was first suggested by Oliver Heaviside in 18 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Geographic News
The National Geographic Society, headquartered in Washington, D.C., United States, is one of the largest nonprofit scientific and educational organizations in the world. Founded in 1888, its interests include geography, archaeology, natural science, the promotion of environmental and historical conservation, and the study of world culture and history. The National Geographic Society's logo is a yellow portrait frame—rectangular in shape—which appears on the margins surrounding the front covers of its magazines and as its television channel logo. Through National Geographic Partners (a joint venture with The Walt Disney Company), the Society operates the magazine, TV channels, a website, worldwide events, and other media operations. Overview The National Geographic Society was founded on January 13, 1888 "to increase and diffuse geographic knowledge". It is governed by a board of trustees whose 33 members include distinguished educators, business executives, former go ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
