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: 1234
convection zone
  زنار ِ همبز   
zonâr-e hambaz

Fr.: zone de convection   

Same as → convective zone.

convective
  همبزی   
hambazi

Fr.: convectif   

Of or relating to → convection.

convective cell
  یاخته‌ی ِ همبزی   
yâxte-y hambazi

Fr.: cellule convective   

A body of → fluid which transports energy through the → convection process.

convective; → cell.

convective cloud
  ابر ِ همبزی   
abr-e hambazi

Fr.: nuage convectif   

Meteorology: A cloud that owes its vertical development, and possibly its origin, to convection.

convective; → cloud.

convective core
  مغزه‌ی ِ همبزی   
maqze-ye hambazi

Fr.: cœur convectif   

The central region of a → massive star where → convection prevails due to steep gradient of temperature relative to pressure.

convective; → core.

convective envelope
  پوشه‌ی ِ همبزی   
puše-ye hambazi

Fr.: enveloppe convective   

1) A → convective zone situated beneath the surface of solar type stars.
2) Stellar models show that → massive stars also possess an outer convective envelope encompassing several percent of the stellar radius. Fast rotation amplifies the size of the convective envelope in → OB stars and developes anisotropic convective envelops (Maeder et al. 2008, A&A 479, L37).

convective; → envelope

convective overshooting
  فرازد ِ همبزی   
farâzad-e hambazi

Fr.: dépassement convectif   

In a → massive star, penetration of the upper layers of the → convective core into the → radiative zone due to → turbulence effects. The enlargement of the convective core results in more luminous stars in theoretical models.

convective; → overshooting.

convective vortex
  گردشار ِ همبزی   
gerdšâr-e hambazi

Fr.: tourbillon convectif   

A common feature of the atmosphere that ranges from small-scale → vortices such as → dust devils, to large-scale systems such as → cyclones.

convective; → vortex.

convective zone
  زنار ِ همبزی   
zonâr-e hambazi

Fr.: zone convective   

A zone inside a star in which → convection takes place; the central → core in → massive stars and the zone underneath → photosphere in low mass stars like the Sun. Recent works predict the presence of a thin convection zone in sufficiently massive main sequence stars which originates from the iron opacity and partial helium ionization. See also → iron convection zone.

convective; → zone.

converge
  همگراییدن   
hamgerâyidan (#)

Fr.: converger   

1) General: To tend to meet in a point; incline toward each other.
2) Math: (of an infinite series) to have a finite sum. (of an improper integral) to have a finite value.

From L.L. convergere "to incline together" from → com- "together" + vergere "to bend."

Hamgerâyidan, from ham- "together," → com- + gerâyidan "to incline toward, verge on; to intend," Mid.Pers. grayidan "to lean, incline; to intend, desire," → diverge.

convergence
  همگرایی   
hamgerâyi (#)

Fr.: convergence   

1) General: Act or state of converging.
2) Math: The property of a → sequence or → series which ensures that it will approach a definite → finite limit. See also: → divergence.

From converg-, from → convergent + -ence, equivalent to → -ance.

Hamgerâyi, verbal noun from hamgerâyidan, → converge.

convergent
  همگرا   
hamgerâ (#)

Fr.: convergent   

Coming together, as a light beam after passing through a convex lens which brings the beam into the focus.

Verbal ddj. from → converge.

converging mirror
  آینه‌ی ِ همگرا   
âyene-ye hamgerâ (#)

Fr.: miroir convergent   

A concave mirror that reflects a parallel beam into a convergent beam.

From → converge + → -ing; → mirror.

conversion
  هاگرد   
hâgard

Fr.: conversion   

The act or process of converting; state of being converted. → convert.

Verbal noun of → convert.

Hâgard, from hâ- prefix denoting "reversal; to," sometimes creating nuance [Dehxodâ], + gard present stem of gardidan, gaštan "to change; to turn;" Mid.Pers. vartitan; Av. varət- "to turn, revolve;" cf. Skt. vrt- "to turn, roll," vartate "it turns round, rolls;" L. vertere "to turn;" O.H.G. werden "to become;" PIE base *wer- "to turn, bend."

conversion factor
  کروند ِ هاگرد   
karvand-e hâgard

Fr.: facteur de conversion   

1) A numerical factor that, by multiplication or division, translates one unit or value into another.
2) In → molecular cloud studies, a factor used to convert the → carbon monoxide (CO) line intensity to → molecular hydrogen (H2) → column density; usually denoted XCO = I(CO) / N(H2). This useful factor relates the observed CO intensity to the cloud mass. A general method to derive XCO is to compare the → virial mass and the 12CO (J = 1-0) luminosity of a cloud. The basic assumptions are that the CO and H2 clouds are co-extensive, and molecular clouds obey the → virial theorem. However, if the molecular cloud is subject to ultraviolet radiation, selective → photodissociation may take place, which will change the situation. Moreover, molecular clouds may not be in → virial equilibrium. To be in virial equilibrium molecular clouds must have enough mass, greater than about 105 solar masses. The way → metallicity affects XCO is a matter of debate, and there is no clear correlation between XCO and metallicity. Although lower metallicity brings about higher ultraviolet fields than in the solar vicinity, other factors appear to be as important as metallicity for the determination of XCO. In the case of the → Magellanic Clouds, XCO(SMC) = 14 ± 3 × 1020 cm-2 (K km s-1)-1, which is larger than XCO (LMC) = 7 ± 2 × 1020 cm-2 (K km s-1)-1. An independent method to derive XCO is to make use of the gamma ray emission from a cloud. The flow of → cosmic ray protons interacts with interstellar low-energy hydrogen nuclei in clouds creating neutral → pions. These pions quickly decay into two gamma rays. It is therefore possible to estimate the number of hydrogen nuclei and hence the cloud mass from the gamma ray counts. Such a gamma-ray based conversion factor is estimated to be 2.0 × 1020 cm-2 (K km s-1)-1 for Galactic clouds, in good agreement with the result obtained from the virial method. However, the gamma ray flux is not well known in general, so this method is uncertain as well. See, e.g., Fukui & Kawamura, 2010 (ARAA 48, 547).

conversion; → factor.

convert
  هاگرد کردن   
hâgard kardan

Fr.: convertir   

1) To change units of one measuring or calculating system into units of another.
2) To transform from one material or state to another.

M.E. converten, O.Fr. convertir, from L. convertere "to turn around, transform," from → com- "together" + vertere "to turn;" cognate with Mod.Pers. gardidan "to change, to turn," → conversion.

Compound verb from hâgard, → conversion, + kardan "to do, to make," → -ize.

converter
  هاگردگر   
hâgardgar

Fr.: convertisseur   

A device that receives data in one form and converts it to another. → analog-to-digital converter.

convert; → -er.

convex
  کوژ   
kuž (#)

Fr.: convexe   

Having a surface that is curved or rounded outward.

From M.Fr. convexe, from L. convexus "vaulted, arched," p.p. of convehere "to bring together," from → com- "together" + vehere "to bring" (cf. Skt. vah- "to carry, lead," vahitra "vehicle," Av. vazaiti "to lead," Mid.Pers. waz-, wazidan "to carry away," Gk. oxos "chariot," PIE base *wegh- "to go, carry, drive").

Kuž "humped," Mid.Pers. kôf "hill, mountain; hump" (Mod.Pers. kuh, "mountain"), kôfik "humpbacked," O.Pers. kaufa-, Av. kaofa- "mountain."

convex lens
  عدسی ِ کوژ   
adasi-ye kuž (#)

Fr.: lentille convexe   

A lens that converges an incident beam of light to a focus.

convex; → lens.

convocation
  هم-وچ، هموچ   
hamvac

Fr.: convocation   

The act of convoking. The state of being convoked.

Verbal noun of → convoke.

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