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: 726
red leak
  نشت ِ سرخ   
našt-e sorx

Fr.: fuite rouge   

Unwanted secondary window in a filter band pass, on the red side of the main window.

red; leak, from M.E leken, from O.N. leka "to drip, leak;" akin to Du. lek, Ger. lech "leaky," O.E. leccan "to moisten."

Našt "leak, leakage," of unknown origin; sorx, → red.

Red Spot
  لکه‌ی ِ سرخ   
lakke-ye sorx (#)

Fr.: Tache rouge   

See → Great Red Spot, on Jupiter.

red; → spot.

red supergiant
  ابَرغول ِ سرخ   
abarqul-e sorx (#)

Fr.: supergéante rouge   

A supergiant star with spectral type K or M. Red supergiants are the largest stars in the Universe, but not necessarily the most massive. Betelgeuse and Antares are the best known examples of a red supergiant.

red; → supergiant.

red transient
  گذرای ِ سرخ   
gozarâ-ye sorx

Fr.: transitoire rouge   

A member of a class of exploding stars that are more luminous than → novae but not as luminous as → supernovae. Moreover, their outburst → light curves have multiple peaks. One of the most characteristic features of red transients is that after exploding they cool down to → late-type → M star and develop circumstellar material rich in molecules and dust. Some of the members of the red transients in our Galaxy are V838V, OGLE-2002-BLG-360, V4332 Sgr, and V1309 Sco.

red; → transient.

red wing
  بال ِ سرخ   
bâl-e sorx

Fr.: aile rouge   

Of a spectral line profile, the → line wing with wavelengths longer than that of the emission or absorption peak.

red; → wing.

red-edge
  لبه‌ی ِ سرخ   
labe-ye soex

Fr.: bord rouge   

A rise in a planet's surface → reflectivity between red → absorbance and → near-infrared reflection due to → vegetation. The red-edge is one of the possible signs of life on distant → habitable  → exoplanets. Its presence is attributed to the chlorophyll molecule and leaf structure. The leaves of land plants reflect sunlight much more efficiently long-ward of this edge than they do in the visible. Although the red-edge position for Earth's vegetation is fixed at around 700-760 nm, that for exoplanets may not necessarily be the same (Takizawa et al., 2017, Nature Scientific Reports 7, Article number: 7561).

red; → edge.

redden
  ۱) سُرخیدن؛ ۲) سرخاندن   
1) sorxidan; 2) sorxândan

Fr.: 1) rougir; 2) faire rougir   

1) (v.intr.) Of a spectral line, to reduce in intensity due to absorption by interstellar dust grains.
2) (v.tr.) Of interstellar dust, to absorb the light that passes through it.

Infinitives from → red.

reddened star
  ستاره‌ی ِ سرخیده   
setâre-ye sorxidé

Fr.: étoile rougie   

A star whose light has undergone → reddening.

Reddened, p.p. of → redden; → star.

reddening
  سُرخش   
sorxeš

Fr.: rougissement   

The process by which light from an astronomical object grows red as it travels through interstellar dust. Dust scatters blue light more than red, thus leaving predominantly red light transmitted.

Verbal noun of → redden.

reddening coefficient
  همگر ِ سرخش   
hamgar-e sorxeš

Fr.: coefficient de rougissement   

A dimensionless quantity determined from the comparison of the observed → Balmer decrements with respect to the theoretical values for given physical conditions of electron temperature and density. The reddening coefficient at Hβ is defined as c(Hβ) = log (I(Hβ)/F(Hβ)), where I(Hβ) and F(Hβ) are → de-reddened and reddened fluxes respectively. Also called logarithmic extinction.

reddening; → coefficient.

reddening function
  کریای ِ سرخش   
karyâ-ye sorxeš

Fr.: fonction de rougissement   

The normalized interstellar extinction at a given wavelength. It is defined by f(λ) = A(λ)/A(Hβ) - 1, where A(λ) is the extinction at the given wavelength and A(Hβ) the extinction at Hβ, with f(Hβ) = 0. It is used to → de-redden observed fluxes: I(λ)/I(Hβ) = F(λ)/F(Hβ).10c(Hβ).f(λ), where I represents the flux in the absence of extinction and F the observed flux affected by extinction, c(Hβ) being the → reddening coefficient.

reddening; → function.

reddening parameter
  پارامون ِ سرخش   
pârâmun-e sorxeš

Fr.: paramètre de rougissement   

A dimensionless quantity characterizing the → interstellar extinction, defined by the total-to-selective extinction ratio: RV = AV/E(B-V). The typical value found for the reddening parameter in the Milky Way is RV ~ 3.1, but it is known to vary from one line of sight to another, from values as 2 to as large as 6. Very large → dust grains would produce extinction with RV → ∞.

reddening; → parameter.

reddening vector
  بُردار ِ سرخش   
bordâr-e sorxeš

Fr.: vecteur de rougissement   

A vector indicating the direction in which interstellar reddening moves the position of a star in a multi-dimensional space of color indices.

reddening; → vector.

redshift
  سرخ‌کیب   
sorxkib

Fr.: décalage vers le rouge   

A shift in the lines of an object's spectrum toward longer wavelengths. Redshift indicates that an object is moving away from the observer. The larger the redshift, the faster the object is moving. Redshift is expressed by z = Δλ/λ = v/c, where λ is the wavelength, Δλ the wavelength shift, v the velocity of the source relative to the observer, and c the → speed of light. When v approaches c, redshift is expressed by the → relativistic formula z = ((1 +v/c)/(1 - v/c))½ - 1.

red; → shift.

redshift space
  فضای ِ سرخ-کیب   
fazâ-ye sorx-kib

Fr.: espace de décalage vers le rouge   

The space corresponding to → redshift measurements, as contrasted with real space. See also → redshift space distortion

redshift; → space.

redshift space distortion
  چولگی ِ فضای ِ سرخ-کیب   
cowlegi-ye fazâ-ye sorx-kib

Fr.: distorsion dûe aux vitesses particulières sur la ligne de visée   

The distortion observed in → redshift space of → galaxy clusters caused by peculiar velocities of the members (→ peculiar velocity). In a perfectly homogeneous → Friedmann-Lemaitre Universe the redshifts would accurately measure radial distances from the observer, and the mapping from real space to redshift space would simply be an identity. In an inhomogeneous Universe the peculiar velocities associated with any inhomogeneous structure will introduce a distortion in this mapping (N. Kaiser, 1987, MNRAS 227, 1). See also: → fingers of God, → Kaiser effect.

redshift; → space; → distortion;.

redshift survey
  بردید ِ سرخ‌کیب   
bardid-e sorx kib

Fr.: relevé de décalages vers le rouge   

A survey of a large region of the sky to measure the redshifts of all the galaxies down to a certain limiting magnitude.

redshift; → survey.

redshift-distance relation
  بازانش ِ سرخ‌کیب-دورا   
bâzâneš-e sorxkib-durâ

Fr.: relation décalage vers le rouge-distance   

The correlation, first established by E. Hubble, between the cosmological recession velocities of galaxies and their distances.

redshift; → distance; → relation.

redshifted line
  خط ِ سرخ‌کیبیده   
xatt-e sorx kibideh

Fr.: raie décalée vers le rouge   

A spectral line whose wavelength does not coincide with its theoretical value and is shifted toward longer wavelengths.

red; → shift; → line.

reduce
  ۱) باز‌هاختن، باز‌هازیدن؛ ۲) کاستن   
1) bâzhâxtan, bâzhâzidan; 2) kâstan

Fr.: réduire   

1) To bring to a certain state, condition, arrangement, etc.
Math.: To change the denomination or form, but not the value, of (a fraction, polynomial, etc.).
Chem.: To add an electron to.
2) To bring down to a smaller extent, size, amount, number, etc.; synonymous with → decrease.

M.E. reducen "to lead back," from O.Fr. reducer, from L. reducere, from → re- "back" + ducere "to bring, to lead."

From bâz-, → re- + Mid.Pers. hâxtan, hâzidan "to lead, guide, persuade," Av. hak-, hacaiti "to attach oneself to, to join," cf. Skt. sacate "accompanies, follows," Gk. hepesthai "to follow," L. sequi "to follow;" PIE *sekw- "to follow."
Kâstan, → decrease.

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