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
circumnuclear
  پیراهسته‌ای   
pirâhasteyi

Fr.: circumnucléaire   

Situated around a → nucleus, as of a → circumnuclear disk.

circum- + → nuclear.

circumnuclear disk
  گرده‌ی ِ پیراهسته‌ای   
gerde-ye pirâhasteyi

Fr.: disque circumnucléaire   

A thick disk of gas and dust clouds surrounding the → Galactic Center up to about 20 → light-years. The disk is very clumpy; the → clumps have densities of several 105 particles/cm3, radii of about 0.3 light-years, and gas temperatures above 100 K. The hydrogen mass of the disk is a few 104 → solar masses. Such circumnuclear disks are present also in other galaxies.

circumnuclear; → disk.

circumpolar
  پیراقطبی   
pirâqotbi (#)

Fr.: circumpolaire   

Situated around or near a pole, as of the Earth or the sky. → circumpolar star.

circum-; → polar.

circumpolar star
  ستاره‌ی ِ پیراقطبی   
setâre-ye pirâqotbi (#)

Fr.: étoile circumpolaire   

Star that, from a given observer's → latitude, does not rise or set, but circles around the → celestial pole. To be circumpolar, a star must have a polar distance that is less than the observer's latitude. Whether a given star is circumpolar at the observer's latitude (φ) may be calculated in terms of the star's → declination (δ). The star is circumpolar if φ + δ ≥ +90° (observer in northern hemisphere), or φ + δ ≤ -90° (observer in southern hemisphere).

circumpolar; → star.

circumscribe
  پیراکشیدن   
pirâkašidan

Fr.: circonscrire   

To draw a line around; encircle.

L. circumscribere "to draw a line around, confine," from → circum- + scribere "write," from PIE *skreibh-, from *sker- "to cut, incise."

Pirâkašidan, from pirâ-, → circum- + kašidan "to draw," Mid.Pers. kašitan, Av. karš- "to draw," Skt. kars-, kársati "to pull, drag, plough."

circumscribed sphere
  سپهر ِ پیراکشیده، کره‌ی ِ ~، گوی ِ ~   
sepehr-e pirâkašidé, kore-ye ~, guy-e ~

Fr.: sphère circonscrite   

A sphere containing a polyhedron (such as a pyramid) all of whose vertices lie on the surface of the sphere. The polyhedron so contained is said to be inscribed in the sphere.

Circumscribed p.p. of → circumscribe; → sphere.

circumsolar
  پیراخورشیدی   
pirâxoršidi

Fr.: circumsolaire   

Surrounding or revolving around the Sun, such as circumsolar space, circumsolar dust.

Circumsolar, from → circum- + → solar.

circumspect
  پیراگاس   
pirâgâs

Fr.: circonspect   

Watchful and discreet; cautious; prudent:

circum-; → suspect.

circumspection
  پیراگاسش   
pirâgâseš

Fr.: circonspection   

Circumspect observation or action; caution; prudence.

circumspect.

circumstance
  پیراستاد   
pirâstâd

Fr.: circonstance   

A condition or fact attending an event and having some bearing on it.

L. circumstantia "surrounding condition," neut. pl. of circumstans, pr.p. of circumstare "to stand around," from → circum- + stare "to stand" from PIE *sta- "to stand."

Pirâstâd, from pirâ-, → circum-, + âstâd, istâd "standing," from istâdan "to stand," Mid.Pers. êstâtan, O.Pers./Av. sta- "to stand, stand still; set," Av. hištaiti, cf. Skt. sthâ- "to stand," âsthâ- "condition, circumstance," Gk. histemi "put, place, weigh," stasis "a standing still," L. stare "to stand."

circumstellar
  پیراستاره‌ای   
pirâsetâreyi

Fr.: circumstellaire   

Surrounding or occurring around a star.

Circumstellar, from → circum- + → stellar.

circumstellar disk
  گرده‌ی ِ پیراستاره‌ای   
gerde-ye pirâsetâreyi

Fr.: disque circumstellaire   

Any concentration of material in the form of a disk orbiting around a star. → accretion disk; → protoplanetary disk.

circumstellar; → disk.

circumstellar dust
  غبار ِ پیراستاره‌ای   
qobâr-e pirâsetâreyi

Fr.: poussière circumstellaire   

Interstellar → dust grains localized around various types of stars, such as → asymptotic giant branch stars. Circumstellar dust occurs in the form of a spherical shell or a disk and is at the origin of an → infrared excess for the central star. See also → circumstellar matter.

circumstellar; → dust.

circumstellar envelope
  پوشه‌ی ِ پیراستاره‌ای   
puše-ye pirâsetâre-yi

Fr.: enveloppe circumstellaire   

A very extensive envelope of cold gaseous materials surrounding evolved cool stars, notably → red giants, → red supergiants (→ Mira variables), or → asymptotic giant branch stars. The typical size of such envelopes is several thousands times that of the stellar radius and their temperature ranges from 1000 to10 K. Circumstellar envelopes result from mass loss from the central star (10-7 to 10-4solar masses per year) and expand with moderate velocities (10 to 15 km sec-1). The low temperature of the envelope is at the origin of the formation of molecules, which in certain conditions provide → maser emission (H2O, OH, SiO). Similarly, dust grains form in the envelope produce an → infrared excess emission.

circumstellar; → envelope.

circumstellar habitable zone
  زنار ِ زیست پذیر ِ پیراستاره‌ای   
zonâr-e zistpazir-e pirâsetâreyi

Fr.: zone habitable circumstellaire   

A zone around a star within which a planet can have temperatures that permit liquid water, depending on the luminosity of the star and the distance of the planet from it.

circumstellar; → habitable zone.

circumstellar maser
  میزر ِ پیراستاره‌ای   
meyzer-e pirâsetâreyi

Fr.: maser circumstellaire   

Maser emission from molecules in the circumstellar envelopes of → red giants, and also from regions around → protostars.

circumstellar; → maser.

circumstellar matter
  ماده‌ی ِ پیراستاره‌ای   
madde-ye pirâsetâreyi

Fr.: matière circumstellaire   

Dust, gas and plasma around stars, generally present in the form of stellar winds or nebulae ejected by the stars.

circumstellar; → matter.

circumstellar outflow
  استچان ِ پیراستاره‌ای   
ostacân-e pirâsetâreyi

Fr.: flot circumstellaire   

A stream of matter into the interstellar medium from a central star.

circumstellar; → outflow.

circumstellar shell
  پوسته‌ی ِ پیراستاره‌ای   
puste-ye pirâsetâreyi

Fr.: coquille circumstellaire   

A shell of dust, molecules, and neutral gas around an evolved star resulting from an intensive mass loss phase, such as the asymptotic giant branch phase for low- and intermediate mass stars and LBVs or supernovae for massive stars.

circumstellar; → shell.

circumzenithal arc
  کمان ِ پیراسرسویی   
kamân-e pirâsarsui

Fr.: arc circumzénithal   

A colorful halo centered on the zenith, appearing when the solar elevation above the horizon is not too high (< 32°).

circum-; → zenithal; → arc.

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