Hickson Compact Group (HCG)
goruh-e hampak-e Hickson
Fr.: groupe compact de Hickson
A list of 100 compact groups of galaxies that were identified by a systematic search of the → Palomar Observatory Sky Survey red prints. Each group contains four or more galaxies, has an estimated mean surface brightness brighter than 26.0 magnitude per arcsec2 and satisfies an isolation criterion.
Being out of sight; concealed.
From M.E., from O.E. hydan, from W.Gmc. *khuthjanan, from PIE *keudh- (cf. Gk. keuthein "to hide, conceal"), from base *(s)keu- "to cover, conceal."
Penhân "hidden," from Mid.Pers. pad nihân, from pad "to, at, for, in" (from O.Pers. paity; Av. paiti "to, toward, in, at;" cf. Skt. práti; Gk. poti) + nihân "concealment, secrecy, hiding place" (Mod.Pers. nahân), from Proto-Iranian *ni-dāna-, from ni- "down; into," → ni- (PIE), + dā- "to put; to establish; to give" (dadâiti "he gives;" cf. Skt. dadâti "he gives;" Gk. didomi "I give;" L. do "I give;" PIE base *do- "to give").
jerm-e penhân (#)
Fr.: masse cachée
Fr.: variable caché
A theory based on the hypothesis that the discrepancies with respect to classical reality found in → quantum mechanics stem from our lack of knowledge about the observed system (→ EPR paradox). According to this hypothesis, the system should be described by additional quantum parameters, of still unknown nature, but different from position, velocity, spin, etc. The hidden variable theory has been ruled out by the violation of → Bell's inequality for all theories with local property, as suggested by the → Aspect experiment.
xušé bandi-ye pâygâni
Fr.: groupement hiérarchique
A model in which a system of self-gravitating particles will gradually aggregate into larger and larger gravitationally bound groups and clusters.
Fr.: cosmologie hiérarchique
A cosmology characterized by clustering of galaxy clusters in increasingly larger systems.
hierarchical multiple system
râžmân-e bastâyi-ye pâygâni
Fr.: système multiple hiérarchique
A → multiple star system in which the stars can be divided into two groups, each of which traverses a larger orbit around the system's center of mass. Each of these smaller groups must also be hierarchical, which means that they must be divided into smaller subgroups which themselves are hierarchical, and so on. Hierarchical multiple systems have long-term dynamical stability.
hierarchical structure formation
diseš-e sâxtâr-e pâygâni
Fr.: formation de structures hiérarchiques
A cosmological → structure formation model in which the smallest gravitationally bound structures (→ quasars and galaxies) form first, followed by → groups, → galaxy clusters, and → superclusters of galaxies.
hierarchical triple system
râžmân-e bastâyi-ye nâpâygâni
Fr.: système multiple non hiérarchique
A triple star system in which the (inner) binary is orbited by a third body in a much wider orbit. → hierarchical multiple system.
A system in which the components are organized in increasingly larger structures.
From O.Fr. ierarchie, from M.L. hierarchia "ranked division of angels," from Gk. hierarchia "rule of a high priest," from hierarches "high priest, leader of sacred rites," from ta hiera "the sacred rites" (neut. pl. of hieros "sacred") + archein "to lead, rule."
Pâygân, from pâyé "step, rank, degree," from pây, pâ "foot, step," from Mid.Pers. pâd, pây; Av. pad- "foot" (cf. Skt. pat; Gk. pos, gen. podos; L. pes, gen. pedis; P.Gmc. *fot; E. foot; Ger. Fuss; Fr. pied; PIE *pod-/*ped-) + -gân suffix forming plural entities, from Mid.Pers. -gânag, -gâna, from Proto-Iranian *kāna-ka-.
boson-e Higgs (#)
Fr.: boson de Higgs
A hypothetical, neutral → elementary particle which plays a key role in the → standard model of → particle physics. This massive particle, whose mass is estimated to be about 125 GeV (→ giga → electron-volts) and a zero → spin, carries the → Higgs field. In the current version of the → electroweak theory, → W boson and → Z boson and all the fundamental constituents (→ quarks and → leptons) get their masses by interacting with the Higgs boson. The Higgs boson is produced by the fusion of two → gluons via a triangular loop of virtual top quarks. In the decay process, a loop of virtual top quarks allows the Higgs boson to decay into two photons. The particle's discovery was announced by → CERN in July 2012.
Named after the Scottish physicist Peter Ware Higgs (1929-), one of the researchers who theorized the existence of this particle in 1964. In fact three groups of physicists almost simultaneously published their results on this subject: François Englert and Robert Brout in August 1964; Peter Higgs in October 1964; and Gerald Guralnik, Carl Hagen, and Tom Kibble in November 1964; → boson.
Fr.: champ de Higgs
A → scalar field supposed to be responsible for the genesis of → inertial mass. According to the → standard model of → particle physics, the Higgs field appeared 10-36 to 10-12 seconds after the → Big Bang, during the → electroweak epoch, when the temperature dropped below a critical threshold. The Higgs field permeates all space, and through its interaction with the fundamental particles it provides those particles with a mass. Any particle that does not interact with the Higgs field, such as the → photon, will be mass-less.
Fr.: mécanisme de Higgs
In the → standard model of → particle physics, a mechanism postulated to endow mass to → elementary particles. Simply put, a background field, called the → Higgs field, becomes locally distorted whenever a particle moves through it. The distortion generates the particle's mass.
boland (#); meh (#); por (#)
1) Situated above the ground or exceeding the common degree or
M.E. heigh, variants hegh, hey, heh; O.E. heh, heah "of great height, lofty, tall," (cf. Du. hoog, O.H.G. hoh, Ger. hoch, Goth. hauhs "high;" also Ger. Hügel "hill"); from PIE *koukos "hill."
Boland "high," variants bâlâ
"up, above, high, elevated, height," borz "height, magnitude"
(it occurs also in the name of the mountain chain Alborz),
Lori dialect berg "hill, mountain;"
Mid.Pers. buland "high;" O.Pers. baršan- "height;"
Av. barəz- "high, mount," barezan- "height;" cf.
Skt. bhrant- "high;" L. fortis "strong" (Fr. & E. force);
O.E. burg, burh "castle, fortified place," from P.Gmc.
*burgs "fortress;" Ger. Burg "castle," Goth. baurgs "city,"
E. burg, borough, Fr. bourgeois, bourgeoisie, faubourg);
PIE base *bhergh- "high."
High Energy Stereoscopic System (H.E.S.S.)
râžmân-e estereyo-ye meh kâruž (H.E.S.S.)
Fr.: Système stéréoscopique de haute énergie (H.E.S.S.)
An array of → IACT telescopes for studying cosmic → gamma rays in the 100 GeV to 100 TeV energy range. The HESS observatory is located in Namibia, southern Africa, at an altitude of 1800 m, and the project is an international collaboration of more than 100 scientists from nine countries. In its Phase I, HESS used four telescopes each consisting of a light collector with a diameter of 13 m and a focal length of 15 m placed at the corners of a square 120 m apart. Each telescope is segmented into 380 round mirror facets of 60 cm diameter and uses a camera consisting of 960 closely packed → photomultiplier tubes. The first of the telescopes went into operation in Summer 2002. Phase II includes a fifth telescope, called Large Cherenkov Telescope (LCT), of 27 m diameter, located in the centre of the initial array. This upgrade lowers the triggering threshold of the HESS array to about 20 GeV, thus broadening the energy window in which gamma-ray astronomy can be done, opening up more opportunities in astrophysical research (see, e.g., Bernlöhr et al. 2003, Astroparticle Physics 20, 111).
H.E.S.S., short for High Energy Stereoscopic System, is also intended to pay homage to Victor F. Hess (1883-1964), an Austrian-American physicist who received the Nobel Prize in Physics in 1936 for his discovery of → cosmic rays.
Fr.: hautes latitudes
The latitude belt roughly between 60 and 90 degrees North and South. Also referred to as the polar region.
high redshift object
Fr.: objet à grand décalage vers le rouge
A galaxy or quasar having a → redshift larger than about 0.8, corresponding to a → look-back time half the present age of the Universe. The qualifier "high" is, however, relative and depends on context and authors' assessment.
owpiš (#), kešand (#), madd (#)
Fr.: marée haute
The state of the → tide when at its highest level.
owpiš (#), barkešand (#), madd(#)
Fr.: marée haute
Also known as → high tide.