An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 1965 Search : ion
expansion parameter
  پارامون ِ سپانش   
pârâmun-e sopâneš

Fr.: paramètre d'expansion   

A → scale factor that relates the size of the Universe R = R(t) at time t to the size of the Universe R0 = R(t0) at time t0 by R = aR0. The expansion parameter represents the history of expansion of the Universe.

expansion; → parameter.


Fr.: espérance, attente   

Statistics: Same as → mathematical expectation, → expected value.

From L. expectare "to await, hope," from → ex- "thoroughly" + spectare "to look," from → specere "to look at," → -scope.

Bayusesš, verbal noun of bayusidan "to expect;" Mid.Pers. pyws- "to hope for, desire" (prefixed *pati-); O.Pers. vasiy "at will, greatly, utterly," vašna- "will, favor;" Av. vas- "to will, desire, wish, long for," vasəmi "I wish," vasna- "will, favor," ušti- "desire, wish, will," vasô, vasə "at one's will." This word is extant in several Mod.Pers. dialects, Tabari vessen "to wish, desire," Gilaki vâssan "to wish, desire," vâsti "desire," Kurd. wistin "to desire, wish," Lâri avessa "to desire," colloquial Tehrâni vâsé "for" (Mid.Pers. vasnâd "because"); cf. Skt. vaś- "to wish, want, desire," váśa- "wish, desire," vasēna "for, because;" Gk. ekon "voluntary;" PIE base *uek- "to wish."


Fr.: explication   

1) The act or process of explaining.
2) A statement made to clarify something and make it understandable.

Verbal noun of → explain.

explicit function
  کریای ِ استاهی   
karyâ-ye ostâhi

Fr.: fonction explicite   

The most usual form of a function in which the dependent variable (written on the left hand side of the Same as → equality sign) is expressed directly in terms of independent variables written on the left (on the right hand side). See also → implicit function.

explicit; → function.

puyeš (#)

Fr.: exploration   

1) An act or instance of exploring or investigating; examination.
2. The investigation of unknown regions.
3) The process of searching for minerals by means of geological studies.
4) Medicine: An examination or investigation for diagnostic purposes, usually involving endoscopy or a surgical procedure.

Verbal noun of → explore.


Fr.: explosion   

The sudden and violent release of mechanical, chemical, or nuclear energy from a confined space which creates a heat wave that travels at → subsonic speeds. → detonation; → deflagration; → implosion.

Verbal noun of → explode.

exponential equation
  هموگش ِ نمایی   
hamugeš-e nemâyi

Fr.: équation exponentielle   

An equation in which unknowns appear as exponents. Examples: 23x + 1 = 32.

exponential; → equation.

exponential function
  کریای ِ نمایی   
karyâ-ye nemâyi

Fr.: fonction exponentielle   

A function in the form of y = bx defined for every → real number x, with positive base b > 1.

exponential; → function.


Fr.: exposition   

1) The act of setting forth information or a viewpoint.
2) Public exhibition or show.

Verbal noun of → expose.


Fr.: expression   

1) The act or an instance of expressing.
2) Math.: A statement using mathematical quantities such as → scalars, → variables, → parameters, → functions, and → sets, as well as → relational and → logical  → operators such as → equality, → conjunction, → existence, → union, etc. (Steven. G. Krantz, ed., Dictionary of Algebra, Arithmetic, and Trigonometry, 2001).

express; → -tion.

ostaneš (#)

Fr.: extension   

1) An act or instance of extending; the state of being extended.
2) Physics: That property of a body by which it occupies space.
3) Math.: A field F is said to be an extension of a field K if K is a subfield of F.
4) Logic: The sum of all individuals or objects to which the comprehension of a term is applied. For example, the extension of the term "dog" is the set of all (past, present and future) dogs in the world.

Verbal noun of → extend.


Fr.: extériorisation   

Verbal noun of → externalize.

externalize + → -tion.

xâmuši (#)

Fr.: extinction   

1) Dimming of light by an intervening medium (the Earth's atmosphere or the interstellar medium). It is usually due to both scattering and absorption.
2) Paleontology: The act or process of dying out or coming to an end, becoming extinct: the extinction of a species; → mass extinction.

Noun of extinct, from L. extinctus, p.p. of extinguere "to quench, wipe out," from → ex- "out" + stinguere "to quench," from PIE base *steig- "to prick, stick, pierce;" cf. Mod.Pers. tiz, tež, tig, tej, tij, tiq "sharp;" Av. tiγra- "pointed," tiγray- "arrow;" → deblur.

Xâmuši, noun of xâmuš "extinguished; silent," Mid.Pers. xâmôš "silent;" cf. Skt. amrs- "to bear patiently."

extinction coefficient
  همگر ِ خاموشی   
hamgar-e xâmuši

Fr.: coefficient d'extinction   

Gradient of apparent magnitude with air mass.

extinction; → coefficient.

extinction correction
  ارشایش ِ خاموشی   
aršâyeš-e xâmuši

Fr.: correction d'extinction   

In → photometric calibration, the correction for energy loss undergone by radiation due to the → atmospheric extinction. Extinction correction is done using → standard stars observed at different → airmasses.

extinction; → correction.

extinction curve
  خم ِ خاموشی   
xam-e xâmuši

Fr.: courbe de l'extinction interstellaire   

A graph representing the variation of the → interstellar extinction against → wavelength. Usually it displays the → normalized values of extinction as a function of (the → inverse) of the wavelength (in → microns). See, e.g., Sandage & Mathis, 1979, Ann. Rev. Astron. Astrophys. 17, 73.

extinction; → curve.

extinction stars
  ستارگان ِ خاموشی   
setâregân-e xâmuši

Fr.: étoiles d'extinction   

Stars specifically observed at selected air masses in view of determining the atmospheric extinction coefficients.

extinction; → star.


Fr.: extraction   

1) The act of extracting or the condition of being extracted.
2) Something obtained by extracting; an extract (

extract; → -tion.

borunyâbeš (#)

Fr.: extrapolation   

Predicting the value of unknown data points by projecting a function beyond the range of known data points.

Verbal noun of → extrapolate.

Faber-Jackson relation
  بازانش فیبر-جکسون   
bâzâneš-e Faber-Jackson

Fr.: relation Faber-Jackson   

An empirical power-law correlation between the luminosity (L) and the velocity dispersion of stars (σ) in the center of a elliptical galaxies. The original relation can be expressed mathematically as: L ∝ σγ, where the index γ is observed to be approximately equal to 4, but depends on the range of galaxy luminosities that is fitted. → Tully-Fisher relation.

After the astronomers Sandra M. Faber and Robert Earl Jackson, who first noted this relation in 1976 (ApJ 204, 668); → relation.

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