An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 142 Search : erg

Fr.: gegenschein   

Same as → gegenschein.

dark energy
  کاروژ ِ تاریک   
kâruž-e târik

Fr.: énergie noire   

A hypothetical form of energy that fills all the space and tends to increase the rate of expansion of the Universe. Assuming the existence of dark energy is a way to explain recent observations that the Universe appears to be expanding at an increasing rate (→ accelerating Universe). Dark energy seems to be a kind of anti-gravity force and is supposed to be related to → vacuum energy. Where gravity pulls things together at the more local level, dark energy tears them apart on the grander scale. The acceleration equation, one of Einstein's equations for the homogeneous Universe, indicates that if the Universe is accelerating, the pressure of the driving component should be strongly negative. The dark energy density relates to the → cosmological constant via: ρ&Lambda = Λc2/(8πG), where G is the → gravitational constant and c the → speed of light. The first indication of dark energy was provided by the observation of → Type Ia supernovae. Other probes of dark energy are: → baryon acoustic oscillations, → weak gravitational lensing, and clusters of galaxies. In the standard model of cosmology, dark energy currently accounts for almost 74% of the total mass-energy of the Universe. Two proposed forms for dark energy are the cosmological constant and exotic component such as → quintessence.

dark; → energy.

dissociation energy
  کاروژ ِ واهزش   
kâruž-e vâhazeš

Fr.: énergie de dissociation   

Energy required to dissociate a molecule. → dissociate.

dissociation; → energy.

vâgerâyidan (#)

Fr.: diverger   

(v.intr.) To move, or extend in different directions from a common point.
Math.: Of a sequence or series, to have no unique limit.

M.L. divergere, from → di- "apart," variant of → dis- + vergere "to bend, turn, incline," from PIE *werg- "to turn," from base *wer- "to turn, bend" (cf. L. vertere "to turn," Av. varət- "to turn," Mod.Pers. gard, gardidan "to turn," Skt. vartate "turns round, rolls," Gk. rhatane "stirrer, ladle," Ger. werden, O.E. weorðan "to become."

Verâyidan, from vâ- "apart," → de-, + gerâyidan "to incline toward; to intend; to make for," infinitive of gerâ, the etymology of which is not clear. Gerâ may be a variant of Mod.Pers. kil "bent, inclined" (k/g and l/r interchanges), from PIE base *klei- "to lean, incline," cognate with L. clinare "to bend" (E. declination, inclination, etc.), Gk. klinein "to cause to slope, slant, incline," Skt. sri- "to lean," O.Pers. θray-, Av. sray- "to lean," P.Gmc. *khlinen (Ger. lehnen, E. lean).

vâgerâyi (#)

Fr.: divergence   

1) The act, fact, or amount of diverging.
2) Math.: A differential → operator that, for a three-dimensional vector function F(x,y,z), is the sum of the → scalar products of the unit vectors and the partial derivatives in each of the three component directions. It is written as div F or ∇ . F = (∂F/∂x)i + (∂F/∂y)j + (∂F/∂z)k, ∇ being the → del operator or → nabla. The divergence of a vector field is a → scalar field. In physics, this operator is used to derive the amount of flux per unit volume leaving an infinitesimal element of volume at a point in a vector field. For example, in an electrostatic field, the divergence of the field is zero unless the volume element contains an electric charge.

From diverge, → diverge, + -ence a noun suffix.

Vâgerâyi, from vâgerâ stem of vâgerâyidan, → diverge, + noun suffix -i.

divergence theorem
  فربین ِ واگرایی   
farbin-e vâgerâyi

Fr.: théorème de flux-divergence   

Same as → Gauss's theorem.

divergence; → theorem.

vâgerâ (#)

Fr.: divergent   

Relating to or causing divergence. Gowing away in different directions from a common point or path.
Math.: Failing to approach a limit.

M.L. divergent-, stem of divergens pr.p. of divergere, from → di- "apart," variant of → dis- + vergere "to bend, turn, incline," from PIE *werg- "to turn," from base *wer- "to turn, bend" (cf. L. vertere "to turn," Av. var ət- "to turn," Mod.Pers. gard, gardidan "to turn," Skt. vartate "turns round, rolls," Gk. rhatane "stirrer, ladle," Ger. werden, O.E. weorðan "to become."

Vâgerâ, agent noun from vâgerâyidan, → diverge + noun suffix -i.

divergent lens
  عدسی ِ واگرا   
adasi-ye vâgerâ (#)

Fr.: lentille divergente   

A lens which causes a parallel beam of light passing through it to diverge or spread out; concave lens. Same as diverging lens and → negative lens.

divergent; → lens.

dry merger
  تشک ِ بی‌گاز   
tašk-e bigâz

Fr.: fusion sans gaz   

A merger between → gas-poor  → early-type galaxies.

dry; → merger.


Fr.: émerger   

1) Move out of or away from something and become visible.
2) To rise or come forth from or as if from water or other liquid (

ex-, + merge, → submerge.


Fr.: émergence   

1) The process of becoming visible after being concealed.
2) The escape of an insect or other invertebrate from an egg, cocoon, or pupal case.
3) The process of coming into existence or prominence (

emerge; → -ence.


Fr.: émergent   

1) Coming into being or notice.
2) Philo.: (of a property) arising as an effect of complex causes and not analyzable simply as the sum of their effects.
3) Ecology: Of or denoting a plant which is taller than the surrounding vegetation, especially a tall tree in a forest (

emerge; → -ent.

emergent ray
  پرتو ِ زمرچنده   
partow-e zomarcandé

Fr.: rayon émergent   

Optics: The → light ray leaving a → medium, in contrast to the → incident ray. If the medium has parallel sides, → angle of incidence and → angle of emergence

emergent; → ray.

endoergic process
  فراروند ِ کاروژگیر   
farâravand-e kâružgir

Fr.: processus endoénergétique   

A nuclear or molecular process in which some of the energy of the incoming particle is absorbed by, or transferred to, the other particle.

endo- + -ergic, a combining form with the meanings "activated by, sensitive to, releasing, resembling the effect produced by the substance or phenomenon specified by the initial element," from → erg, → energy + → -ic; → process.

Farâravand, → process; kâružgir, from kâruž, → energy, + gir present stem of gereftan "to take, seize, catch" (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").

  ۱) کاروژمند؛ ۲) کاروژی   
1) kâružmand; 2) kâruži

Fr.: 1) de grande énergie, énergique; 2) énergétique   

1) Having a relatively high amount of energy.
2) Of or relating to energy.

energy + -t + → -ic.

energetic solar particles
  ذره‌های ِ خورشیدی ِ کاروژمند   
zarrehâ-ye xoršidi-ye kâružmand

Fr.: particules solaires énergétiques   

Electrons and atomic nuclei ejected by solar flares, travelling with velocities amounting to a fraction of the velocity of light, and energies mostly in the range 1-100 million → electronvolts (eV), but occasionally as high as 15 billion eVs. Also known as solar → cosmic rays.

Energetic, from Gk. energetikos, from energe-, → energy, + -tikos a suffix, equivalent in meaning to → -ic, occurring in adjectives; → solar; → particle.

Zarrehâ plural of zarré, → particle; xoršidi, → solar; kâružmand from kâruž, → energy, + -mand possession suffix.


Fr.: énergétique   

The total energy relations and transformations of energy within a particular physical, chemical, or biological system.

energy + -t + → -ics.


Fr.: énergie   

In physics, capacity for doing work.

From M.Fr. energie, from L.L. energia, from Gk. energeia "force in action, activity, operation," from energos "active, working," from en- "in, at" + ergon "work," from PIE base *werg- "to work" (cf. Av. varəz- "to work, do, perform, exercise;" Mod.Pers. varz-, varzidan "to labor, exercise, practise;" Arm. gorc "work;" Lith. verziu "tie, fasten, squeeze," vargas "need, distress;" Goth. waurkjan; O.E. wyrcan "work," wrecan "to drive, hunt, pursue").

Kâruž, literally "work strength," from kâr + . The first component kâr "work," Mid.Pers kâr, Mod./Mid.Pers. kardan "to do, to work," Mid.Pers. kardan; O.Pers./Av. kar- "to do, make, build," Av. kərənaoiti "he makes;" cf. Skt. kr- "to do, to make," krnoti "he makes, he does," karoti "he makes, he does," karma "act, deed;" PIE base kwer- "to do, to make." The second component, , from Mid.Pers. ôž "strength" (ôžômand "strong"), Av. aogah-, aojah- "strength" (aojahvant- "strong") Skt. ojas- "strength" (ojasvant- "strong"); L. augustus "venerable," L.L. augmentare "to increase," from augere "to increase, enlarge, enrich;" Lith. augu "to grow;" Gk. auxo "increase;" Goth. aukan "to grow, increase;" O.E. eacien "to increase"); PIE *augos- "force," *aug- "to increase."

energy cascade
  پی‌شار ِ کاروژ   
peyšâr-e kâruž

Fr.: cascade d'énergie   

The → turbulent process whereby → kinetic energy is transformed into heat by the action of nonlinear coupling which transfers the energy from large eddies (→ eddy) to smaller and smaller eddies, finally arriving at → dissipative scales dominated by → viscosity (direct cascade). In the simplest case (3D homogeneous hydrodynamic turbulence), the resulting energy distribution is the → Kolmogorov spectrum. The reverse process also exists (inverse cascade) whereby energy is transferred to larger and larger eddies.

energy; → cascade.

energy density
  چگالی ِ کاروژ   
cagâli-ye kâruž

Fr.: densité d'énergie   

The amount of energy in the form of radiation per unit volume, expressed in ergs cm-3. In particular, the energy density of blackbody radiation at temperature T is aT4, where the radiation constant a = 7.56 × 10-15 erg cm-3 (K)-4.

energy; → density.

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