An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 120 Search : ore

Fr.: folkolre   

The traditional beliefs, legends, customs, etc., of a people; lore of a people (

Coined by English scholar and antiquary William John Thoms (1803-1885), from → folk, + lore "traditional knowledge or belief," from M.E., O.E. lar cognate with Du. leer, Ger. Lehre "teaching," E. learn.

Palgvâr, literally "customs of people," from palg, → folk, + vâr "custom, rule, law" (Dehxodâ).

araš (#)

Fr.: avant bras   

The part of the arm between the → elbow and the → wrist.

From fore- a prefix meaning "before; front; superior," related to → per-; → arm.

Araš, variant ârenj "elbow;" Mid.Pers. âranj; O.Pers. arašan- "cubit;" Av. arəθnâ- "elbow;" Skt. aratni- "elbow," Iranian stem aratan-, araθn-, borrowed from Iranian into General Slavic as aršin "ell."


Fr.: avant-plan   

The ground or parts situated, or represented as situated, in the front; the portion of a scene or stellar field nearest to the viewer. → background.

From fore, from O.E. fore (prep.) "before, in front of;" (adv.) "before, previously" (cf. O.H.G. fora, Ger. vor, Goth. faiura); from PIE *per-/*pr- (cf. Skt. pura "before, formerly;" Av. paro "before;" Hittite para- "on, forth;" Gk. paros "before," para "from beside, beyond," peri "around, about, toward," pro "before;" L. pro "before, for, instead of," prae "before," per "through, for") + ground, from M.E., from O.E. grund; akin to O.H.G. grunt "ground."

Pišzaminé, from piš- "before; in front," from Mid.Pers. pêš "before, earlier;" O.Pers. paišiya "before; in the presence of" + ziminé "ground," from zamin "earth, ground" → earth.

foreground absorption
  درشم ِ پیش-زمینه   
daršam-e pišzaminé

Fr.: absorption d'avant-plan   

Loss of radiant energy received from an astronomical object due to the presence of absorbing matter situated between the object and observer.

foreground; → absorption.

jangal (#)

Fr.: forêt   

1) A large tract of land covered with trees and underbrush; woodland (
2) In → graph theory, a → graph which contains no → cycles. The connected components of a forest are → trees.

M.E., from O.Fr. forest, probably from L.L. forestis (silva) "the outside woods," from L. foris "outside."

Jangal "a wood, forest, a vast land with plenty of trees;" cf. Skt. jangala- "arid , sparingly grown with trees and plants."

Fourier theorem
  فربین ِ فوریه   
farbin-e Fourier

Fr.: théorème de Fourier   

Any finite periodic motion may be analyzed into components, each of which is a simple harmonic motion of definite and determinable amplitudes and phase.

Fourier analysis; → theorem.

Gauss's theorem
  فربین ِ گاؤس   
farbin-e Gauss

Fr.: théorème de Gauss   

The total normal induction over any closed surface drawn in an electric field is equal to 4π times the total charge of electricity inside the closed surface. Gauss's theorem applies also to other vector fields such as magnetic, gravitational, and fluid velocity fields. The theorem can more generally be stated as: the total flux of a vector field through a closed surface is equal to the volume → integral of the vector taken over the enclosed volume. Also known as → divergence theorem, Ostrogradsky's theorem, and Gauss-Ostrogradsky theorem.

gauss; → theorem.

giant magnetoresistance (GMR)
  مغنات-ایستادگی ِ کلان، ایستادگی ِ مغناتیسی ِ ~   
meqnât-istâdegi-ye kalân, istâdegi-ye meqnâtisi-ye ~

Fr.: magnétorésistance géante   

A quantum mechanical phenomenon where the resistance of certain materials drops dramatically upon application of a magnetic field in certain structures composed of alternating layers of magnetic and nonmagnetic metals. The basis of the GMR is the dependence of the electrical resistivity of electrons in a magnetic metal on the direction of the electron spin, either parallel or anti-parallel to the magnetic moment of the layers. The 2007 Nobel Prize in physics was awarded to the French physicist Albert Fert (1938-) and German physicist Peter Grünberg (1939-) for the discovery of GMR.

giant; magneto- combining form of → magnet; → resistance.

Helmholtz's theorem
  فربین ِ هلمهولتس   
farbin-e Helmholtz

Fr.: théorème de Helmholtz   

A → decomposition theorem, whereby a continuous → vector field, F, can be broken down into the sum of a → gradient and a → curl term: F = -∇φ + ∇ xA, where φ is called the → scalar potential and A the → vector potential.

Helmholtz free energy; → theorem.

hot core
  مغزه‌ی ِ داغ   
maqze-ye dâq

Fr.: cœur chaud   

Same as → hot molecular core.

hot; → core.

hot molecular core (HMC)
  مغزه‌ی ِ مولکولی ِ داغ   
maqze-ye molekuli-ye dâq

Fr.: cœur moléculaire chaud   

A relatively small, dense, and hot → molecular clump occurring in regions of → massive star formation. HMCs have diameters ≤ 0.1 pc, densities ≥ 107 cm-3, and temperatures ≥ 100 K. The densest hot cores are traced in → ammonia (NH3) and possess densities of 108 cm-3, sizes down to 0.05 pc and temperatures of up to 250 K. Hot molecular cores are generally associated with → compact H II regions and → ultracompact H II regions. High angular resolution observations suggest that HMCs are internally heated by embedded sources, since temperature and density increases toward the center as expected if star formation is occurring close to the core center. Same as → hot core.

hot; → molecular; → core.

nâdidé engâštan (#)

Fr.: ignorer, négliger   

To set aside, e.g. → ignorable coordinate.

From Fr. ignorer, from L. ignorare "not to know, disregard," from ignarus "not knowing, unaware," from in- "not," → un-, + gnarus "aware, acquainted with," related to gnoscere "to → know".

Nâdidé engâštan literally "supposed not seen," from nâdidé "not seen" (from nâ- "not," → un- + didé "seen," p.p. of didan "to see," → sight) + engâštan "to suppose" (→ hypothesis).

inner core
  مغزه‌ی ِ درونی   
maqze-ye daruni

Fr.: noyau interne   

The central part of the → Earth's core, composed of solidified → iron and → nickel, and extending from a depth of about 5100 km to the center of the Earth, at 6360 km. Its radius is about 1/3 that of the whole core and is effectively decoupled from the → mantle due to the molten nature of the surrounding → outer core. The radius of the inner core is defined by a small increase in → compressional wave velocity at a radius of about 1200 km. Its density is about 12 g/cm3. The → temperature of the inner core has been estimated at 5000-7000 °C.

inner; → core.

International Ultraviolet Explorer (IUE)

Fr.: IUE   

A satellite dedicated to spectroscopic observations of astronomical objects in ultraviolet wavelengths, launched in 1978. It was an international collaboration between → NASA, the → European Space Agency (ESA), and the United Kingdom's Science and Engineering Research Council. It operated until September 1996 and collected over 70,000 spectra. IUE consisted of a 45-cm telescope (f/15) equipped with two spectrographs operating in the ranges 1850-3300 Å and 1150-2000 Å. Each spectrograph had a high-resolution and a low-resolution mode with resolutions of about 0.2 Å and 6 Å respectively.

international; → ultraviolet; → explorer.

iron core
  مغزه‌ی ِ آهن   
maqze-ye âhan

Fr.: cœur de fer   

1) Electromagnetism: A bar of → soft iron that passes through a coil and serves to increase the → inductance of the coil.
2) The innermost part of some planets, such as Mercury, Venus, and Earth, which have a molten iron-rich core.
3) The end point in the evolution of stars with a mass above ~ 10 → solar masses. Such a star evolves in several stages over millions of years during which various → thermonuclear reactions take place in the star core. Each stage results in a core composed of heavier elements. The process ends when → silicon burning produces a core of iron-nickel. Since iron has the maximum → binding energy per → nucleon, the → nuclear fusion cannot proceed further. The iron core shrinks and heats up. It is maintained against → gravitational collapse by → electron degeneracy pressure, but it continues to grow as Si burning adds more iron. When the core reaches its → Chandrasekhar limit, it becomes unstable and undergoes the → core collapse.

iron; → core.

JUpiter ICy moons Explorer (JUICE)
  پویشگر ِ مانگهای ِ یخی ِ هرمز   
Puyešgar-e Mânghâ-ye Yaxi-ye Hormoz

Fr.: Jupiter ICy moons Explorer   

An interplanetary mission currently in development by the → European Space Agency planned for launch in 2020. It is aimed mainly at in-depth studies of three potentially ocean-bearing satellites, → Ganymede, → Europa, and → Callisto. JUICE will complete a unique tour of the Jupiter system including several flybys of each planet-sized world, culminating with orbit insertion around Ganymede, the largest moon in the Solar System, followed by nine months of operations in its orbit. JUICE will carry the most powerful scientific payload ever flown to the outer Solar System. It consists of 10 state-of-the-art instruments plus one experiment that uses the spacecraft telecommunication system with ground-based instruments.

Jupiter; → icy; → explorer; → moon.

kinematically decoupled core (KDC)
  مغزه‌ی ِ جنبشیکانه واجفسریده   
maqze-ye jonbešikâné vâjafsaridé

Fr.: cœur cinématiquement découplé   

A central, tightly bound stellar subsystem observed in some elliptical galaxies which rotates in the opposite direction with respect to the main body of the → elliptical galaxy. Elliptical galaxies are thought to be the result of the → merger of two or more sizable galaxies. A plausible scenario for how counter-rotating cores could form in such a merger is as follows. If at least one of the galaxies has a core region that is fairly tightly bound by the galaxy's gravity, and the direction in which the two galaxies orbit each other before merging is opposite to the direction of rotation of stars in that tightly bound core, it is likely that, after the merger, the tightly bound core will end up as the core of the new, larger galaxy, while retaining its original sense of rotation. The surrounding stars, on the other hand, will rotate in a different way dictated by the orbital motion of the galaxies around each other, before the merger. While this is a plausible scenario, it can only explain some of the counter-rotating cores. Recently A. Tsatsi et al. (2015, ApJ 802, L3) have shown that although the two → progenitor galaxies are initially following a → prograde orbit, strong reactive forces during the merger can cause a short-lived change of their orbital spin; the two progenitors follow a → retrograde orbit right before their final coalescence. This results in a central kinematic decoupling and the formation of a large-scale (~2 kpc radius) counter-rotating core at the center of the final elliptical-like merger remnant, while its outer parts keep the rotation direction of the initial orbital spin.

kinematical; → decouple; → core.

Larmor's theorem
  فربین ِ لارمور   
farbin-e Larmor

Fr.: théorème de Larmor   

If a system of → charged particles, all having the same ratio of charge to mass (q/m), acted on by their mutual forces, and by a central force toward a common center, is subject in addition to a weak uniform magnetic field (B), its possible motions will be the same as the motions it could perform without the magnetic field, superposed upon a slow → precession of the entire system about the center of force with angular velocity ω = -(q/2mc)B.

Larmor frequency; → theorem.

Liouville's theorem
  فربین ِ لیوویل   
farbin-e Liouville

Fr.: théorème de Liouville   

A key theorem in statistical mechanics of classical systems which states that the motion of phase-space points defined by Hamilton's equations conserves phase-space volume.

After Joseph Liouville (1809-1882), a French mathematician; → theorem.

local Lorentz invariance
  ناورتایی ِ لورنتز ِ محلی   
nâvartâyi-ye Lorentz-e mahali

Fr.: invariance de Lorentz locale   

Einstein equivalence principle.

local; → Lorentz; → invariance.

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