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erupt osdaridan Fr.: entrer en éruption To burst forth; to eject matter (of a star, volcano, geyser, etc.). → eruptive variable. From L eruptus "burst forth, broken out," p.p. of erumpere "to break out, burst forth," from → ex- "out" + rumpere "to break, rupture." Osdaridan, from os-, → ex- + daridan "to tear, rend, lacerate;" Mid.Pers. darridan "to tear, split;" Av. dar- "to tear," dərəta- "cut," auua.dərənant- "shattering;" cf. Skt. dar- "to crack, split, break, burst," darati "he splits;" Gk. derein "to flay," derma "skin;" P.Gmc. *teran; O.E. teran; E. tear; Ger. zerren "to pull, to tear," zehren "to undermine, to wear out;" PIE base *der- " to split, peel, flay." |
eruption osdareš Fr.: éruption 1) An act, process, or instance of erupting; something that is erupted or ejected. Verbal noun of → erupt. |
eruptive osdareši Fr.: éruptif Relating to, formed by, characterized by, or producing → eruption. |
eruptive object barÂxt-e osdareši Fr.: objet éruptif An astronomical object such as a → variable star, a → nova, a → young stellar object, etc. characterized by abrupt changes of luminosity. |
eruptive prominence zabâne-ye osdareši Fr.: protubérance éruptive A huge solar prominence which has previously been quiescent but suddenly starts to lift up from the → photosphere with velocities of several hundred km/s and escapes into the → interplanetary space. Eruptive prominences with the highest velocities have been observed at 1300 km/s, reaching heights of 1 million km above the photosphere. Such prominences are often observed at the solar limb, in association with → coronal mass ejections. On the Sun's disk, the equivalent phenomenon is an eruptive filament. → eruptive; → prominence |
eruptive variable vartande-ye osdareši Fr.: variable éruptive same as → cataclysmic variable. |
euphemism xošguyi, xošzabâni Fr.: euphémisme An inoffensive word or phrase substituted for one considered offensive or hurtful, especially one concerned with religion, sex, death, or excreta (TheFreeDictionary.com). From Gk. euphemismos, from euphemizein "speak with fair words, use words of good omen," from → eu- "well," + pheme "speech, voice, talk," from phanai "to speak," ultimately from PIE *bha- "to speak, tell, say;" cf. Skt. bhanati "speaks;" L. fari "to say," fabula "tale, story," fama "talk, rumor, report; reputation;" Armenian ban, bay "word, term." Xošguyi, xošzabâni, literally "pleasant talking, ~ speach," from xoš "well, pleasant," → eu- + guyi verbal noun of goftan "to say, talk, speak," → logic; zabâni, from zabân, → language. |
Europa (Jupiter II) Europâ, orupâ (#) Fr.: Europe The sixth of → Jupiter's known moons and the fourth largest; it is the second of the → Galilean satellites. With a diameter of 3140 km, Europa is slightly smaller than Earth's Moon. Its mass is 4.80 × 1022 kg, i.e. 1.5 times less massive than Earth Moon. Its distance to Jupiter is 670,900 km, or about 9 Jovian radii. Its → orbital period is 3.55 Earth days which equals its → rotation period. Europa's density is 3.0 g cm-3, typical of a mixture of rocks including → ice. Its high → albedo (0.67) suggests that its surface is mostly → water ice. The → surface temperature of Europa ranges between about 125 K (-150 °C) at the equator and about 50 K (-220 °C) at the poles. There are few → impact craters on Europa, because its surface is too active and therefore young. The most striking features of Europa's surface are structures called → lineae and → lenticulae. The thickness of the ice crust could range between a few kilometers to a few tens of kilometers. It is now believed that there is an ocean of salty water, up to 100 km deep, flowing under Europa's ice. Europa's ocean is kept liquid due to → tidal heating by Jupiter. In Gk. mythology, Europa was a Phoenician princess (Agenor's daughter) abducted to Crete by Zeus, who had assumed the form of a white bull, and by him the mother of Minos, Sarpedon, and Rhadamanthys. |
EX Lupi EX Gorg Fr.: EX Lupi A classical → T Tauri star, and the EXor prototype, subject to sporadic outbursts. It remains at about V = 13.2 mag for extended periods to brighten to as much as V = 8.4 mag (1955-1956). When EX Lupi is at minimum, it resembles a classical T Tauri star of type M0. At outburst this spectrum is veiled by a hot continuum, the equivalent widths of the optical-region emission lines decrease, and reverse P Cygni absorption components appear at the higher Balmer lines. The outbursts are believed to be due to episodic infall onto the M0 star. → FU Orionis objects. E and X, letters of alphabet; Lupi, genitive of → Lupus. |
exit pupil mardomak-e osraft Fr.: pupille de sortie In an → optical system, the → image of the → aperture stop formed by the elements following it. See also → entrance pupil. |
first dredge-up borunkašid-e naxost Fr.: premier dragage The → dredge-up occurring after core hydrogen burning as the core contracts before helium burning ignites (on the ascending giant branch). The hydrogen envelope becomes convective and this convective zone penetrates deep into the core dredging up material that has been processed by the central nuclear reactions. As a result the abundances of helium and nitrogen are boosted. |
follow-up observation nepâheš-e peygir Fr.: An observation which expands previous observations and aims at obtaining complementary data in particular with other telescopes/instruments. Follow-up, from follow, from O.E. folgian, fylgan "to follow, pursue," from W.Gmc. *fulg- (cf. O.Fris. folgia, M.Du. volghen, Ger. folgen "to follow") + up, O.E. up, uppe (cf. Du. op, Ger. auf "up, upward"), from PIE base *upo "up from below;" cf. O.Pers./Av. upā; Skt. úpa; Gk. hypo; L. sub, → hypo-; → observation. Nepâheš, → observation; peygir, from pey "after; step," related to pâ "foot, step, track," → foot, + gir present stem of gereftan "to take, seize" (Mid.Pers. griftan, Av./O.Pers. grab- "to take, seize," cf. Skt. grah-, grabh- "to seize, take," graha "seizing, holding, perceiving," M.L.G. grabben "to grab," from P.Gmc. *grab, E. grab "to take or grasp suddenly;" PIE base *ghrebh- "to seize"). |
full super Moon abar pormâng, abar pormâh Fr.: pleine lune de périgée Same as → perigee full Moon. |
galvanic couple joft-e gâlvâni Fr.: couple galvanique A pair of dissimilar conductors, commonly metals, in electrical contact. |
Ganymede (Jupiter III) Gânumedes Fr.: Ganymède The seventh and largest of → Jupiter's known satellites. This → Galilean satellite has a diameter of 5270 km, slightly larger than Mercury, a mass about 1.48 × 1023 kg (about 2 Earth Moons); an → orbital period of 7.155 days, and an → eccentricity of e = 0.0015. It was discovered by Galileo and Marius in 1610. The mean → surface temperature of Ganymede is -160 °C. It is the only moon known to have a → magnetosphere. In Gk. mythology, Ganymedes, a unusually beautiful prince of Troy who was abducted to Olympus by Zeus and made the cup-bearer of the gods. |
gauge group goruh-e gaz (#) Fr.: groupe de jauge The mathematical group associated with a particular set of gauge transformations. |
gravitational coupling constant pâyâ-ye jafsari-ye gerâneši Fr.: constante de couplage gravitationnel The dimensionless gravitational constant defined as the gravitational attraction between pair of electrons and normally given by: αG = (Gme2) / (ħc) = (me / mP)2 ~ 1.7518 × 10-45, where ħ is → Planck's reduced constant, c the → speed of light, me is the → electron mass, and mP is the → Planck mass. → gravitational; → coupling; → constant. |
group 1) goruh (#); 2) goruhândan; goruhidan Fr.: 1) groupe; 2) grouper; se grouper 1a) Any collection or assemblage of persons or things considered together or
regarded as belonging together; e.g.
→ Local Group of galaxies. From Fr. groupe "cluster, group," from It. gruppo "cluster, packet, knot," likely from P.Gmc. *kruppa "round mass, lump." Goruh "group," from Mid.Pers. grôh "group, crowd." |
group theory negare-ye goruh (#) Fr.: théorie des groupes A branch of mathematics concerned with structures called → groups and the description of their properties. Group theory provides a powerful formal method of analyzing abstract and physical systems in which → symmetry is present. It has a very considerable use in physics, especially → quantum mechanics, notably in analyzing the → eigenstates of energy of a physical system. |
group velocity tondâ-ye goruh Fr.: vitesse de groupe The velocity at which the envelope of a → wave packet propagates, vgr = dω/dk, at k0 (the central value of k). The group velocity can be equal to, larger, or smaller than the → phase velocity. |
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