An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 244 Search : up
eruption
  اسدرش   
osdareš

Fr.: éruption   

1) An act, process, or instance of erupting; something that is erupted or ejected.
2) → flare.
3) Geology: The ejection of molten rock, steam, etc., as from a volcano or geyser.

Verbal noun of → erupt.

eruptive
  اسدرشی   
osdareši

Fr.: éruptif   

Relating to, formed by, characterized by, or producing → eruption.

eruption; → -ive.

eruptive object
  بر‌آخت ِ اسدرشی   
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; → object.

eruptive prominence
  زبانه‌ی ِ اسدرشی   
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
  ورتنده‌ی ِ اسدرشی   
vartande-ye osdareši

Fr.: variable éruptive   

same as → cataclysmic variable.

eruptive; → variable.

euphemism
  خوشگویی، خوشزبانی   
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)
  اءوروپا، اروپا   
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 گرگ   
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
  مردمک ِ اسرفت   
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.

exit; → pupil.

first dredge-up
  برونکشید ِ نخست   
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.

first; → dredge-up.

follow-up observation
  نپاهش ِ پیگیر   
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 "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
  ابر پرمانگ، ابر پرماه   
abar pormâng, abar pormâh

Fr.: pleine lune de périgée   

Same as → perigee full Moon.

full; → super-; → Moon.

galvanic couple
  جفت ِ گالوانی   
joft-e gâlvâni

Fr.: couple galvanique   

A pair of dissimilar conductors, commonly metals, in electrical contact.

galvanism; → couple.

Ganymede (Jupiter III)
  گانومدس   
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
  گروه ِ گز   
goruh-e gaz (#)

Fr.: groupe de jauge   

The mathematical group associated with a particular set of gauge transformations.

gauge; → group.

group
  ۱) گروه؛ ۲) گروهاندن؛ گروهیدن   
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.
1b) Math.: A set of elements a, b, c, ..., finite or infinite in number, with a rule for combining any two of them to form a "product," subject to the following four axioms: → closure axiom, → associative axiom, → identity axiom, and → inverse axiom.
2a) (v.tr.) To place or associate together in a group.
2b) (v.intr.) To be part of a group.

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
  نگره‌ی ِ گروه   
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; → theory.

group velocity
  تندای ِ گروه   
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.

group; → velocity.

grouping
  گروهش   
goruheš

Fr.: groupement   

The act or process of uniting into groups.
A collection of things assembled into a group.
The occurence of several astronomical objects, usually of the same category, in a region of the sky.

Verbal noun of → group.

halo occupation distribution (HOD)
  واباژش ِ هگش ِ هاله   
vâbâžeš-e hageš-e hâlé

Fr.: distribution d'occupation de halo   

The → probability distribution of the → number of galaxies that a host → dark matter halo of a given mass contains. HOD is a powerful theoretical frame to populate dark matter halos with luminous galaxies. More specifically, it describes the bias between galaxies and dark matter by specifying (a) the probability P(N|M) that a halo of → virial mass M contains N galaxies of a particular class and (b) the relative spatial and velocity distributions of galaxies and dark matter within halos.

halo; → occupation; → distribution.

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