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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

   Homepage   
   


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

<< < D l dar dat de deb dec dec dec def deg del dem dep der det deu dia dif dif dig dio dir dis dis dis dis dis DO dop dou dra Dub dus dyn dyn > >>

Number of Results: 690
de Broglie equation
  هموگش ِ دوبروی   
hamugeš-e de Broglie

Fr.: équation de de Broglie   

According to the → de Broglie hypothesis, which has been verified by experiments, every → particle of matter, whatever its nature, has a characteristic → wavelength associated with its wavelike quantum aspect. The de Broglie equation gives the equivalent wavelength of a moving particle: λ = h/mv, where h is → Planck's constant, m the mass of the particle, and v its velocity.
See also: → de Broglie wavelength, → Davisson-Germer experiment.

Named after Louis Victor de Broglie (1892-1987), French physicist, creator of a new field in physics, wave mechanics, who won the Nobel prize in physics in 1929. → equation

de Broglie hypothesis
  انگاره‌ی ِ دوبروی   
engâre-ye de Broglie

Fr.: hypothèse de de Broglie   

The suggestion by Louis de Broglie in 1924 whereby if → electromagnetic waves possess particle properties (→ particle nature), then it might be reasonable to suppose that material particles, such as → electrons, should possess wave properties (→ wave nature). The de Broglie hypothesis was based on the intuitive feeling that nature seems to have strong attachment to symmetry. In other words, if radiation has particle-like properties, then material particles should possess wave-like properties. At the time no direct experimental evidence was present for the validity of this suggestion. The first confirmation of de Broglie's hypothesis was provided by the → Davisson-Germer experiment. See also → wave-particle duality;

de Broglie equation; → hypothesis.

de Broglie wavelength
  موج-طول ِ دوبروی   
mowjtul-e de Broglie

Fr.: longueur d'onde de Broglie   

The wavelength of the wave associated with a → particle as given by the → de Broglie equation.

de Broglie equation; → wavelength.

de Sitter Universe
  گیتی ِ دوسیتر   
giti-ye de Sitter

Fr.: Univers de de Sitter   

A solution to → Einstein's field equations of → general relativity which contains no ordinary matter (ΩM = 0) or radiation (ΩR = 0), is → Euclidean (k = 0), but has a → cosmological constantΛ > 0). The Universe expands exponentially forever. This solution was the first model expanding of → expanding Universe. See also → empty Universe, → Milne Universe.

After the Dutch mathematician and physicist Willem de Sitter (1872-1934) who worked out the model in 1917; → universe.

de Vaucouleurs law
  قانون ِ دووکولور   
qânun-e de Vaucouleurs

Fr.: loi de Vaucouleurs   

A mathematical expression describing the → surface brightness profile of a typical → elliptical galaxy, whereby the projected luminosity distribution varies as exp(-R)1/4.

de Vaucouleurs radius; → law.

de Vaucouleurs radius
  شعاع ِ دووکولور   
šo'â'-e de Vaucouleurs

Fr.: rayon de Vaucouleurs   

An → isophotal radius of a galaxy, where the → surface brightness in the B band falls to 25 mag arcsec-2.

After the French-born American astronomer Gérard de Vaucouleurs (1918-1995); → radius.

de-
     
vâ- (#), foru- (#)

Fr.: de-   

A prefix occurring in loanwords from L. to indicate: 1) Opposition, reversal: decentralize, decode, deactivate, de-emphasis 2) Removal from: dethrone. 3) Reduction, degradation: declass, devalue. 4) reversal: detract, detect. 5) Derivation from: derive, deverbative.

M.E., from O.Fr. de-, des-, partly from L. de- "from, down, away," and partly from L. → dis-.

Prefix vâ- denoting "reversal, opposition; separation; repetition; open; off; away," variant of bâz-, from Mid.Pers. abâz-, apâc-; O.Pers. apa- [pref.] "away, from;" Av. apa- [pref.] "away, from," apaš [adv.] "toward the back;" cf. Skt. ápāñc "situated behind."
Foru- "down, downward; below; beneath," Mid.Pers. frôt "down, downward," O.Pers. fravata "forward, downward," Skt. pravát- "a sloping path, the slope of a mountain."

de-excitation
  فرو انگیزش   
foru-angizeš

Fr.: désexcitation   

Transition from an excited energy state to a lower energy level, as in spectral line formation or particle emission from an atomic nucleus.

From → de- + → excitation.

de-orbit
  وامداریدن   
vâmadâridan

Fr.: désorbiter   

To cause a spacecraft to leave its operational orbit to enter a descent phase or to change course.

From → de- + → orbit.

de-orbiting
  وامدارش   
vâmadâreš

Fr.: désorbitage   

Of a spacecraft, the act or process of departing from an operational orbit. → de-orbit.

Noun form of → de-orbit.

de-projection
  وا-فراشانش   
vâ-farâšâneš

Fr.: déprojection   

A method for estimating the real orientation of a field and/or related velocities/separations from two-dimensional images.

de-; → projection.

de-redden
  واسرخیدن   
vâsorxidan

Fr.: dérougir   

To correct the intensity or flux of a spectral line by eliminating the → reddening effect of → interstellar dust.

De-redden, from → de- + redden verb of → red.

Vâsorxidan, from vâ-, → de-, + sorxidan verb of sorx, → red.

de-reddened magnitude
  برز ِ واسرخیده   
borz-e vâsorxidé

Fr.: magnitude dérougie   

A magnitude which has been corrected for the interstellar reddening.

De-reddened, p.p. of → de-redden; → magnitude.

Borz, → magnitude; vâsorxidé p.p. of vâsorxidan, → de-redden.

de-reddening
  واسرخش   
vâsorxeš

Fr.: dérougissement   

The process that de-reddens. The state of being de-reddened.

Verbal noun of → de-redden.

deactivate
  فروژیراندن   
foružirândan

Fr.: désactiver   

To cause to be → inactive; remove the → effectiveness of (Dictionary.com).

de-; → activate.

dead
  مرده   
mordé (#)

Fr.: mort   

1) Deprived of life.
2) No longer producing or functioning. → dead pixel.

M.E. deed, O.E. dead "dead;" cf. O.S. dod, Dan. død, Swed. död, Du. dood, O.H.G. tot, Ger. tot; PIE *dhou-toz-, from base *dheu- "to die."

Mordé "dead," p.p. of mordan, mir- "to die," → death.

dead pixel
  پیکسل ِ مرده   
piksel-e mordé

Fr.: pixel mort   

Of a → CCD detector, a pixel that is not sufficiently active.

dead; → pixel.

death
  مرگ   
marg (#)

Fr.: mort   

The act of dying; the end of life.

M.E. deeth, O.E. deað (cf. O.S. doth, O.Fris. dath, Du. dood, O.H.G. tod, Ger. Tod, O.N. dauði, Dan. død, Swed. död, Goth. dauþas "death"), from *dheu- "to die" + *-thuz "-th;"

Marg "death," from Mid.Pers. marg "death;" Av. mahrka- "death," mərəxš- "ruin;" related to Mod.Pers. mordan (present stem mir-) "to die;" Mid.Pers. murdan "to die;" O.Pers. mrt- "to die," amriyta "dies," martiya- "(mortal) man" (Mod.Pers. mard "man"); Av. mərəta- "died;" cf. Skt. mar- "to die," mrti- "death," marc- "to damage, hurt, injure;" PIE base *mor-/*mr- "to die." Cognates in other IE languages: Gk. emorten "died," ambrotos "immortal;" L. morior "I die," mortuus "dead" (Fr. mourir "to die," mort "dead"); Arm. merani- "to die;" O.C.S. mrutvu "dead;" O.Ir. marb; Welsh marw "died;" O.E. morþ "murder;" Lith. mirtis.

debate
  ۱) وازت؛ ۲) وازتیدن   
1) vâzat; 2) vâzatidan

Fr.: 1) débat; 2) débattre   

1a) A → discussion, as of a public question in an assembly, involving opposing viewpoints.
1b) A formal contest in which the affirmative and negative sides of a proposition are advocated by opposing speakers.
2) To engage in argument or discussion, as in a legislative or public assembly (Dictionary.com).

M.E. debaten, from O.Fr. debatre, literally "to fight," from → de- "down, completely," + batre "to beat," → beat.

Vâzat, from vâ-, → de-, + zat- (Baluci žat-) variant of zad-, zadan "to strike, beat", → beat.

debias
  ورک زدودن   
varak zodudan

Fr.: soustraire le biais   

To substract the → bias from a flat-field or science frame obtained using an electronic detector.

Debias, from → de- + → bias.

Varak zodudan, from varakbias + zodudan "to polish, clean," Mid.Pers. uzdātan, Av. uzdā-, from uz-, → ex-, + dā- "make, create."

<< < D l dar dat de deb dec dec dec def deg del dem dep der det deu dia dif dif dig dio dir dis dis dis dis dis DO dop dou dra Dub dus dyn dyn > >>