An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 742
radiative process
  فراروند ِ تابشی   
farâravand-e tâbeši

Fr.: processus radiatif   

An process in which an excited state loses its absorbed energy by emission of radiation. → non-radiative process.

radiative; → process.

radiative recombination
  بازمیازش ِ تابشی   
bâzmiyâzeš-e tâbeši

Fr.: recombinaison radiative   

The process by which an ionized atom binds a free electron in a → plasma to produce a new atomic state with the subsequent radiation of photons.

radiative; → recombination.

radiative shock
  تش ِ تابشی، شوک ِ ~   
toš-e tâbeši, šok-e ~

Fr.: choc radiatif   

A → shock wave in which the → time-scale for → cooling is much shorter than the appropriate → dynamical or → evolutionary time-scale of the system that drives the shock. Radiative shock waves are believed to play a key role in a variety of different astrophysical environments, including → magnetic cataclysmic variables, → jets from → young stellar objects, → accretion in → T Tauri stars, → colliding stellar winds, and → supernova remnants.

radiative; → shock.

radiative transfer
  تراواژ ِ تابش، ~ تابشی   
tarâvâž-e tâbeš, ~ tâbeši

Fr.: transfer radiatif, ~ de rayonnement   

The process by which the → electromagnetic radiation passes through a medium that may contain any combination of → scatterers, → absorbers, and → emitters.

radiative; → transfer.

radiative transfer equation
  هموگش ِ تراوَژ ِ تابش   
hamugeš-e tarâvaž-e tâbeš

Fr.: équation de transfer radiatif, ~ ~ de rayonnement   

The equation that describes the → radiative transfer. It states that the → specific intensity of radiation Iσ during its propagation in a medium is subject to losses due to → extinction and to → gains due to → emission: dIσ/dx = - μσ . Iσ + ρ . jσ, where x is the coordinate along the → optical path, μσ is the → extinction coefficient, ρ is the mass → density, and jσ is the → emission coefficient per unit mass.

radiative; → transfer; → equation.

radiative transition
  گذرش ِ تابشی   
gozareš-e tâbeši

Fr.: transition radiative   

A transition between two states of an atomic or molecular entity, the energy difference being emitted or absorbed as photons.

radiative; → transition.

radiative zone
  زنار ِ تابشی   
zonâr-e tâbeši

Fr.: zone radiative   

The region of a star in which the energy generated by → nuclear fusion in the core is transferred outward by → electromagnetic radiation and not by → convection. Such zones occur in the interior of low-mass stars, like the Sun, and the envelopes of → massive star. The radiative zone of the Sun starts at the edge of the core of the Sun, about 0.2 solar radii, and extends up to about 0.7 radii, just below the → convective zone.

radiative; → zone.

radiatively driven wind
  باد ِ تابشی   
bâd-e tâbeši

Fr.: vent radiatif   

Same as → radiation-driven wind

radiative; → drive; → wind.

  ریشه، ریشگی، ریشال   
rišé (#), rišegi (#), rišâl

Fr.: racine   

1) Math.: The indicated root of a quantity, as denoted by an expression written under the → radical sign.
2) Chemistry: A group of atoms present in a series of compounds which conserves its identity in the course of chemical changes which affect the rest of the molecule. For example, the → cyano radical and → hydroxyl group.

M.E., from L.L. radicalis "of or having roots," from → radix "root."


radical axis
  آسه‌ی ِ پایه   
âse-ye pâyé

Fr.: axe radical   

Of two circles, the straight line containing all points P such that the lengths of the tangents from P to the two circles are equal.

radical; → axis.

radical sign
  نشانه‌ی ِ ریشال، ~ ریشگی   
nešâne-ye rišâl, ~ rišegi

Fr.: signe radical   

The symbol √ placed before a number or quantity to indicate the extraction of the square root. The value of a higher (the n-th) root is indicated by a raised positive digit (n) in front of the symbol, as in 3√ (cube root). The first known occurrence of this symbol was in the book Die Cross, published in 1525, by the German mathematician Christoff Rudolff.

radical; → symbol.


Fr.: rayons   

Plural form of → radius.


  ۱)؛ ۲) رادیو؛ ۳) پرتو، رادیو   
1); 2) râdio; 3) partow, râdio

Fr.: radio   

1) An apparatus for receiving or transmitting radio broadcasts.
2) Pertaining to the → radio waves of the → electromagnetic radiation.
3) As a prefix, indicating → radition or → radioactivity.

1); 2) Short from radiophone and radio-telegraphy.
3) Combining form of → radiation.

Râdio, loan from Fr., as above; partowray.

radio Arc
  کمان ِ رادیویی   
kamân-e râdio-yi

Fr.: arc radio   

A large number of narrow filaments in → radio continuum occurring toward the → Galactic Center, about 15 to 20 arc-minutes (some 50 parsecs in projection) north of → Sgr A*. The radio Arc is the prototype of → non-thermal filaments (NTFs) and resolves into a set of more than a dozen vertical filaments with lengths of about 30 pc distributed symmetrically with respect to the → Galactic equator (Yusef-Zadeh et al. 1984, Nature 310, 557). Among more than 100 NTFs found in the Galactic center region, the Arc is the only one known to show inverted spectrum with a → spectral index α = +0.3 (Law et al. 2008, ApJS 177, 515, and references therein). This implies a very hard energy spectrum of particles for a source of → synchrotron radiation.

radio; → arc.

radio astronomy
  رادیو-اخترشناسی، اخترشناسی ِ رادیویی   
râdio axtaršenâsi, axtaršenâsi-ye râdioi

Fr.: radio astronomie   

The branch of astronomy that deals with the study of the Universe by means of → radio waves.

radio; → astronomy.

radio burst
  بلک ِ رادیویی   
belk-e râdio-yi

Fr.: sursaut radio   

A burst of emission in the radio frequencies of the electromagnetic spectrum.

radio; → burst.

radio continuum emission
  گسیل ِ پیوستار ِ رادیویی   
gosil-e peyvastâr-e râdio-yi

Fr.: émission de continuum radio   

A → continuum emission with frequencies in the radio range of the electromagnetic spectrum.

radio; → continuum; → emission.

radio counterpart
  همتای ِ رادیویی   
hamtâ-ye râdio-yi

Fr.: contrepartie radio   

The representation in → radio wavelengths of an astronomical object that has emission in other parts of the → electromagnetic spectrum.

radio; → counterpart.

radio emission
  گسیل ِ رادیویی   
gosil-e râdio-yi

Fr.: émission radio   

Electromagnetic radiation carried by → radio waves.

radio; → emission.

radio flux
  شار ِ رادیویی   
šârr-e râdioyi

Fr.: flux radio   

Total radiation in radio wavelengths going out from the 2π solid angles of a hemisphere. → flux.

radio; → flux.

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