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James E. Pringle
James Edward Pringle (born 20 January 1949) is a British astrophysicist. He is a professor of theoretical astronomy at the Institute of Astronomy, Cambridge part of the University of Cambridge. His research is focused mainly on astrophysical fluid dynamics and accretion discs, including, for example, the formation of stars and planets, accretion of matter onto black holes, and formation of jets by accretion flows. In a 1984 paper, he and John Papaloizou showed that accretion disks in anisotropic stellar systems with constant specific angular momentum are unstable to non-axisymmetric global modes. This phenomenon is now known as the Papaloizou–Pringle instability. He was awarded the Eddington Medal The Eddington Medal is awarded by the Royal Astronomical Society for investigations of outstanding merit in theoretical astrophysics. It is named after Sir Arthur Eddington. First awarded in 1953, the frequency of the prize has varied over the ye ... in 2009. References Exter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Black Hole
A black hole is a region of spacetime where gravity is so strong that nothing, including light or other electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole. The boundary of no escape is called the event horizon. Although it has a great effect on the fate and circumstances of an object crossing it, it has no locally detectable features according to general relativity. In many ways, a black hole acts like an ideal black body, as it reflects no light. Moreover, quantum field theory in curved spacetime predicts that event horizons emit Hawking radiation, with the same spectrum as a black body of a temperature inversely proportional to its mass. This temperature is of the order of billionths of a kelvin for stellar black holes, making it essentially impossible to observe directly. Objects whose gravitational fields are too strong for light to escape were fi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Living People
Related categories * :Year of birth missing (living people) / :Year of birth unknown * :Date of birth missing (living people) / :Date of birth unknown * :Place of birth missing (living people) / :Place of birth unknown * :Year of death missing / :Year of death unknown * :Date of death missing / :Date of death unknown * :Place of death missing / :Place of death unknown * :Missing middle or first names See also * :Dead people * :Template:L, which generates this category or death years, and birth year and sort keys. : {{DEFAULTSORT:Living people 21st-century people People by status ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1949 Births
Events January * January 1 – A United Nations-sponsored ceasefire brings an end to the Indo-Pakistani War of 1947. The war results in a stalemate and the division of Kashmir, which still continues as of 2022. * January 2 – Luis Muñoz Marín becomes the first democratically elected Governor of Puerto Rico. * January 11 – The first "networked" television broadcasts take place, as KDKA-TV in Pittsburgh, Pennsylvania goes on the air, connecting east coast and mid-west programming in the United States. * January 16 – Şemsettin Günaltay forms the new government of Turkey. It is the 18th government, last One-party state, single party government of the Republican People's Party. * January 17 – The first Volkswagen Beetle, VW Type 1 to arrive in the United States, a 1948 model, is brought to New York City, New York by Dutch businessman Ben Pon Sr., Ben Pon. Unable to interest dealers or importers in the Volkswagen, Pon sells the sample car to pay his ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eddington Medal
The Eddington Medal is awarded by the Royal Astronomical Society for investigations of outstanding merit in theoretical astrophysics. It is named after Sir Arthur Eddington. First awarded in 1953, the frequency of the prize has varied over the years, at times being every one, two or three years. Since 2013 it has been awarded annually. Recipients Source is unless otherwise noted. See also * List of astronomy awards * List of physics awards * List of prizes named after people This is a list of awards that are named after people. A B C D E F G H I J K L M N O P R S T U - V W Y Z See also *Lists of awards *List of eponyms A ''list'' is any set of items in a row ... References External links Winners {{Royal Astronomical Society Astronomy prizes Physics awards Awards established in 1953 British science and technology awards Astronomy in the United Kingdom Royal Astronomical Society 1953 establishments ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Papaloizou–Pringle Instability
The Papaloizou-Pringle Instability (PPI) is a scientific discovery made in 1984 by theoretical physicist John Papaloizou and James E. Pringle which proposes that tori, or accretion disks, in anisotropic stellar systems with constant specific angular momentum In physics, angular momentum (rarely, moment of momentum or rotational momentum) is the rotational analog of linear momentum. It is an important physical quantity because it is a conserved quantity—the total angular momentum of a closed syst ... are unstable to non-axisymmetric global modes. History Linear analysis of the instability was first outlined by Papaloizou and Pringle in 1984. Relativistic numerical studies confirmed the effects of the instability, probed the non-linear effects primarily responsible for setting the final amplitude of the global modes, and showed that the resulting matter distribution exhibited counter-rotating epicyclic vortices (also called ''planets''). References {{DEFAULTSORT:Papaloizou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Papaloizou
John Christopher Baillie Papaloizou FRS (born 1947) is a British theoretical physicist. Papaloizou is a professor at the Department of Applied Mathematics and Theoretical Physics (DAMTP) at the University of Cambridge. He works on the theory of accretion disks, with particular application to the formation of planets. He received his D.Phil. in 1972 from the University of Sussex under the supervision of Roger J. Tayler. The title of his thesis is ''The Vibrational Instability in Massive Stars''. He discovered the Papaloizou-Pringle instability together with Jim Pringle in 1984. Papaloizou also made major contributions in various areas such as the radial-orbit instability, toroidal modes in stars and different instabilities in accretion disks. The asteroid 17063 Papaloizou is named after John Papaloizou. Awards 2003 Fellow of the Royal Society Fellowship of the Royal Society (FRS, ForMemRS and HonFRS) is an award granted by the judges of the Royal Society of London to i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polar Jet
An astrophysical jet is an astronomical phenomenon where outflows of ionised matter are emitted as an extended beam along the axis of rotation. When this greatly accelerated matter in the beam approaches the speed of light, astrophysical jets become relativistic jets as they show effects from special relativity. The formation and powering of astrophysical jets are highly complex phenomena that are associated with many types of high-energy astronomical sources. They likely arise from dynamic interactions within accretion disks, whose active processes are commonly connected with compact central objects such as black holes, neutron stars or pulsars. One explanation is that tangled magnetic fields are organised to aim two diametrically opposing beams away from the central source by angles only several degrees wide Jets may also be influenced by a general relativity effect known as frame-dragging. Most of the largest and most active jets are created by supermassive black holes (SMBH) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planet
A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a young protostar orbited by a protoplanetary disk. Planets grow in this disk by the gradual accumulation of material driven by gravity, a process called accretion. The Solar System has at least eight planets: the terrestrial planets Mercury, Venus, Earth and Mars, and the giant planets Jupiter, Saturn, Uranus and Neptune. These planets each rotate around an axis tilted with respect to its orbital pole. All of them possess an atmosphere, although that of Mercury is tenuous, and some share such features as ice caps, seasons, volcanism, hurricanes, tectonics, and even hydrology. Apart from Venus and Mars, the Solar System planets generate magnetic fields, and all except Venus and Mercury have natural satellites. The giant pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Professor
Professor (commonly abbreviated as Prof.) is an academic rank at universities and other post-secondary education and research institutions in most countries. Literally, ''professor'' derives from Latin as a "person who professes". Professors are usually experts in their field and teachers of the highest rank. In most systems of academic ranks, "professor" as an unqualified title refers only to the most senior academic position, sometimes informally known as "full professor". In some countries and institutions, the word "professor" is also used in titles of lower ranks such as associate professor and assistant professor; this is particularly the case in the United States, where the unqualified word is also used colloquially to refer to associate and assistant professors as well. This usage would be considered incorrect among other academic communities. However, the otherwise unqualified title "Professor" designated with a capital letter nearly always refers to a full profes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Star
A star is an astronomical object comprising a luminous spheroid of plasma held together by its gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night, but their immense distances from Earth make them appear as fixed points of light. The most prominent stars have been categorised into constellations and asterisms, and many of the brightest stars have proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. The observable universe contains an estimated to stars. Only about 4,000 of these stars are visible to the naked eye, all within the Milky Way galaxy. A star's life begins with the gravitational collapse of a gaseous nebula of material composed primarily of hydrogen, along with helium and trace amounts of heavier elements. Its total mass is the main factor determining its evolution and eventual fate. A star shines for most of its active life due t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Accretion Disc
An accretion disk is a structure (often a circumstellar disk) formed by diffuse material in orbital motion around a massive central body. The central body is typically a star. Friction, uneven irradiance, magnetohydrodynamic effects, and other forces induce instabilities causing orbiting material in the disk to spiral inward towards the central body. Gravitational and frictional forces compress and raise the temperature of the material, causing the emission of electromagnetic radiation. The frequency range of that radiation depends on the central object's mass. Accretion disks of young stars and protostars radiate in the infrared; those around neutron stars and black holes in the X-ray part of the spectrum. The study of oscillation modes in accretion disks is referred to as diskoseismology. Manifestations Accretion disks are a ubiquitous phenomenon in astrophysics; active galactic nuclei, protoplanetary disks, and gamma ray bursts all involve accretion disks. These disks ve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
