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: 685
Dumbbell Nebula (M27, NGC 6853)
  میغ ِ دمبل   
miq-e dambel

Fr.: Nébuleuse de l'Haltère   

One of the brightest planetary nebulae; it lies in the constellation → Vulpecula at a distance of about 1000 light-years. It was discovered by Charles Messier in 1764.

Dumbbell "a short bar with weights at each end that is used for exercise," from dumb + bell. When viewed in a small telescope, the brighter portion of the nebula shows like a bipolar geometry, hence the name; → nebula.

Dambel loanword from dumbbell, as above; → nebula.

duodecennial
  دوازده‌سالی   
davâzdahsâli (#)

Fr.: duodécennal   

Consisting of twelve → years.

From L. duodecennium, from duodecim "tweleve," from duo, → two, + decem, → ten, + annus "year," → annual.

Davâzdahsâli, from davâzdah "twelve," from do, → two, + dah, → ten + sâl, → year.

duodecennial animal calendar
  گاهشمار ِ دوازده‌سالی ِ جانوری   
gâhšomâr-e davâzdahsâli-ye janevari (#)

Fr.: calendrier duodécennal   

A → lunisolar calendar in which the years are named after each of the following twelve animals: rat, ox, tiger, hare, dragon, snake, horse, sheep, monkey, cock, dog, pig. An animal presides over one year in the twelve-year cycle, which is then repeated. The calendar was/is mainly used by central Asian cultures (Khotanese, Sogdians, Buddhists, Kucheans, Mongols, and Chinese). It was also used in Iran after the Mongol invasion in the thirteenth century.

duodecennial; → animal; → calendar.

duplicate
  ۱) دوتاییدن، دوتا کردن؛ ۲) دوتاکرد   
1) dotâyidan, dotâ kardan; 2) dotâkard

Fr.: 1) faire un double de; 2) double, copie exacte   

1) To make an exact copy of.
2) A copy exactly like an original.

From L. duplicatus, p.p. of duplicare "to double," from duo, → two + plicare "to fold," → multiply.

Dotâyidan, "to double," infinitive from dotâyi, → double.

duplication
  دوتایش، دوتاکرد   
dotâyeš, dotâkard

Fr.: duplication   

An act or instance of duplicating; the state of being duplicated.

Verbal noun of → duplicate.

dust
  غبار، گرد   
qobâr(#), gard (#)

Fr.: poussière   

Tiny pieces of solid material, such as carbon and silicate grains, in the → interstellar medium that are about 0.1-1.0 micron in size. → Dust grains embedded in → molecular clouds may be significantly larger.

O.E. dust, akin to O.H.G. tunst "storm," from P.Gmc. *dunstaz, from PIE base dhem-/dhemə- "to smoke, to blow," cf. Skt. dhūmá "smoke," Mod.Pers. dam "smoke; to blow, breathe," Av. dāδmainya- "blowing up," Gk. thumiao "to fumigate, burn incense," thymos "spirit, mind, soul," L. fumus "smoke," Ossetic dymyn/dumun "to smoke, blow up," Lith. dumai "smoke."

Qobâr, from Ar.; gard "dust," Mid.Pers. gart, gard.

dust analogue
  آناگویه‌ی ِ غبار   
ânâguye-ye qobâr

Fr.: analogue de poussière   

A chemical compound produced in laboratory experiments to simulate real → interstellar dust grains and thus study them.

dust; → analogue.

dust coagulation
  ماسش ِ غبار، رچش ِ ~   
mâseš-e qobâr, roceš-e ~

Fr.: coagulation de la poussière   

A process of formation of → dust grains in → interstellar medium and → protoplanetary disks, in which randomly colliding aggregates may stick together.

dust; → coagulation.

dust devil
  دیو-باد   
div-bâd

Fr.: tourbillon de poussière   

A small but vigorous → whirlwind, usually of short duration, rendered visible by → dust, → sand, and → debris picked up from the ground (Meteorology Glossary, Amer. Meteo. Soc.). See also → dust storm, → dust whirl.

dust; → devil.

dust emission
  گسیل ِ غبار   
gosil-e qobâr

Fr.: émission des poussières   

Thermal emission in infrared from interstellar → dust grains receiving photons. Dust grains absorb ultraviolet and visible light emitted by nearby stars and re-radiate in the infrared wavelengths. Since the infrared light is of lower energy than the ultraviolet/visible light, the difference goes into heating the dust grain. Typical temperatures for interstellar grains are tens of degrees Kelvin.

dust; → emission.

dust feature
  آرنگ ِ غبار   
ârang-e qobâr

Fr.: marque de poussière, signature de ~, motif spectral de ~   

An emission or absorption mark in the spectrum of an astronomical object, the origin of which is attributed to the presence of dust in the object or on the line of sight.

dust; → feature.

dust grain
  دانه‌ی ِ غبار   
dâne-ye qobâr (#)

Fr.: grains de poussière   

A small, solid flake of → graphite and/or → silicates coated with water ice, found in the → interstellar medium or the → interplanetary medium. Dust grains are irregularly shaped with sizes from microns to Angstroms (→ very small grain; → big grain; → PAH). It is believed that the dust is mainly formed in the cool outer layers of → red giants and dispersed in the interstellar medium. In dense environments, such as → molecular clouds and around → protostars, dust grains grow due to collisions (→ grain growth). Therefore, dust grains in → protostellar disks should be larger than interstellar grains. Dust grains absorb and scatter optical and ultraviolet light and re-radiate in infrared (→ dust emission). Dust acts as a catalyst in the interstellar medium, because molecules form via reactions on the surface of dust grains.

dust; → grain.

dust lane
  باریکه‌ی ِ غبار   
bârike-ye qobâr

Fr.: bande de poussière   

A narrow, elongated structure of absorbing matter seen running over extended emission objects such as nebulae and galaxies.

dust; lane, from O.E. lane, lanu "narrow hedged-in road," cf. Du. laan "lane," O.N. lön "row of houses," of unknown origin.

Bâriké "a narrow thing," from bârik "narrow," from Mid.Pers. bārīk "narrow," Av. bāra-, as in tiži.bāra- "sharp-edged," from brāy- "to cut," Mod.Pers. bor-, boridan "to cut;" qobârdust.

dust model
  مدل ِ غبار   
model-e qobâr

Fr.: modèle de poussière   

A model of → dust grains conceived to describe the observed → interstellar extinction properties. It is characterized by the abundance of the different → chemical elements locked up in the dust, and by the → composition, → morphology, and → size distribution of its individual grains. For example, → MRN dust model.

dust; → model.

dust obscuration
  تیره‌شد پت غبار   
tirešod pat qobâr

Fr.: obscurcissement par la poussière   

The → absorption of → electromagnetic radiation from an astrophysical object by → dust grains associated with that object.

dust; → obscuration.

Tiregi, → obscuration, pat, → by; qobâr, → dust.

dust scattering
  پراکنش ِ غباری، ~ پت غبار   
parâkaneš-e qobâri, ~ pat qobâr

Fr.: diffusion par la poussière   

The scattering of → photons by → dust grains.

dust; → scattering.

dust settling
  نیاشش ِ غبار   
niyâšeš-e qobâr

Fr.: dépose de poussières   

A process occurring in → protoplanetary disks whereby relatively large → dust grains settle to the disk midplane. These grains, with sizes from → micron to → millimeter, grow from smaller dust grains and will eventually give rise to a planetary system.

dust; → settling.

dust storm
  غبار-توفان   
qobâr-tufân

Fr.: tempête de poussière   

An unusual, frequently severe weather condition characterized by strong winds and dust-filled air over an extensive area. See also → dust devil, → dust whirl.

dust; → storm.

dust tail
  دنباله‌ی ِ غباری   
donbâle-ye qobâri (#)

Fr.: queue de poussière   

The tail of a → comet which is caused by → solar radiation pressure forcing the dust particles away from the → coma in a curved arch. Also called a → Type II tail.

dust; → tail.

dust temperature
  دمای ِ غبار   
damâ-ye qobâr

Fr.: température de poussière   

An indication of the heat amount received by → dust grains from the ambient → radiation field. Dust temperature depends on the optical properties and → sizes of grains (i.e., on the way they → absorb and → emit radiation) as well as on the → interstellar radiation field. Most of the visible and → ultraviolet radiation in galaxies from stars passes through clouds of particles and heats them. This heating leads to re-radiation at much longer wavelengths extending to the millimeter.

dust; → temperature.

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