An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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radio recombination line
  خط ِ بازمیازش ِ رادیویی   
xatt-e bâzmiyâzeš-e râdioyi

Fr.: raie de recombinaison radio   

A → recombination line whose wavelength lies in the radio range of the electromagnetic spectrum. Radio recombination lines are the result of electronic transitions between high energy levels (n > 50) in an atom or ion.

radio; → recombination line.

radio signal
  نشال ِ رادیویی   
nešâl-e râdio-yi

Fr.: signal radio   

A signal in the → radio frequency region of the → electromagnetic spectrum.

radio; → signal.

radio silence
  بیدنگی ِ رادیویی   
bidengi-ye râdioyi

Fr.: silence radio   

A condition in which all fixed or mobile equipments capable of radio transmitting in an area are kept inoperative, typically for the duration of some sensitive time period. The term has both military and civilian applications.

radio; → silence.

radio source
  رادیو-خن، خن ِ رادیویی   
râdio-xan, xan-e râdioyi

Fr.: radio source, source radio   

A point or small portion of the sky giving stronger radio emission than the sky in its vicinity.

radio; → source.

radio spectrum
  بیناب ِ رادیویی   
binâb-e râdio-yi

Fr.: spectre radio   

That part of the → electromagnetic spectrum that includes → radio waves.

radio; → spectrum.

radio star
  رادیو-ستاره، ستاره‌ی ِ رادیویی   
râdio setâré, setâre-ye râdioyi

Fr.: étoile radio   

A star which is a source of emission at radio frequencies. Radio stars include pulsars, flare stars, binary star systems in which mass is transferred from one component to the other, and some X-ray stars.

radio; → star.

radio storm
  توفان ِ رادیویی   
tufân-e radioyi (#)

Fr.: orage radio   

Strong radio frequency radiation from the Sun, occurring in association with eruptions of solar flares or other causes of solar activity.

radio; → storm.

radio Sun
  خورشید ِ رادیویی   
xoršid-e râdioyi (#)

Fr.: Soleil radio   

The image of the Sun obtained from its electromagnetic radiation in radio frequencies. The apparent size of the radio Sun depends of the frequency of the signal, since different radio frequencies originate from various atmospheric layers of the Sun.

radio; → sun.

radio survey
  بردید ِ رادیویی   
bardid-e râdio-yi

Fr.: relevé radio   

A map or series of images of a region of sky obtained in → radio wavelengths of the → electromagnetic radiation.

radio; → survey.

radio telescope
  رادیو-تلسکوپ، تلسکوپ ِ رادیویی   
râdio-teleskop (#), teleskop-e râdioyi (#)

Fr.: radio télescope   

A telescope whose receiver is sensitive to → radio waves.

radio; → telescope.

radio wave
  موج ِ رادیویی   
mowj-e râdioyi (#)

Fr.: ondes radio   

The → electromagnetic radiation with the longest → wavelengths (and lowest energies), ranging from 0.3 mm to several km. Radio waves form a very broad category, which includes the → submillimeter waves (with a wavelength of 0.3-1 mm) and → microwave regions (1 mm to several cm).

radio; → wave.

radio wavelength
  موج-طول ِ رادیویی   
mowjtul-e râdioyi

Fr.: longueur d'onde radio   

The → electromagnetic radiation with a wavelength ranging from 1 mm to several 100 km. See so → radio wave.

radio; → wavelength.

radio window
  روزنه‌ی ِ رادیویی   
rowzane-ye râdioyi (#)

Fr.: fenêtre radio   

A range of electromagnetic radiation in the radio frequencies to which the Earth's atmosphere is transparent.

radio; → window.

radio-loud quasar
  کو‌آسار ِ رادیویی ِ خروشان   
kuâsâr-e râdioyi-ye xorušân

Fr.: quasar puissant en radio   

A quasar that has the same characteristics as a → radio-quiet quasar with the addition of having strong radio emissions.

radio; loud, from O.E. hlud "making noise;" cf. M.Du. luut, Du. luid, O.H.G. hlut, Ger. laut "loud;" → quasar.

Kuâsâr, → quasar; râdioyi, adj. of → radio; xorušân "shouting aloud, roaring," from xorušidan "to shout, cry aloud, roar;" Mid.Pers. xrôšitan "to shout."

radio-quiet quasar
  کو‌آسار ِ رادیویی ِ آرام   
kuâsâr-e râdioi-ye ârâm

Fr.: quasar faible en radio   

A type of quasar with weak radio emission. These types of quasars have strong emissions in both the optical and X-ray spectra. Within the optical spectrum, both broad and narrow emission lines are present. Their host is usually an elliptical galaxy, but less commonly, it might be a spiral. → radio-load quasar.

radio; quiet, M.E., from O.Fr. quiete, from L. quies (genitive quietis) "rest, quiet;" → quasar.

Kuâsârquasar; → radio; ârâm "quiet" (Mid.Pers. râm "peace," râmenidan "to give peace, pleasure," râmišn "peace, pleasure;" Av. ram- "to stay, rest;" cf. Skt. ram- "to stop, stand still, rest, become appeased;" Gk. erema "quietly, gently;" Goth. rimis "rest;" Lith. rãmas "rest").


Fr.: radioactive   

Possessing, or pertaining to, → radioactivity.

radio + → active.

radioactive dating
  سن‌یابی ِ پرتو-ژیرا   
sen yâbi-ye partow-žirâ

Fr.: datation radioactive   

Determining the age of an object from the → radioactive decay of its constituting material. The technique consists of comparing the → abundance ratio of a → radioactive isotope to its → decay product. This will yield the number of half-lives that have occurred since the sample was formed. More specifically, if an object is made up of 50 % decay product then it has gone through 1 → half-life. 75% decay product equals 2 half-lives, 87.5% decay product equals 3 half-lives, 93.76% decay product equals 4 half-lives, and so on. For example, the decay product of → uranium-238 (238U) is → lead-206 (206Pb). The half-life of 238U is 4.5 billion years. Hence, if the sample has gone through two half-lives, it is 9 billion years old. See also: → radiocarbon dating.

radioactive; → dating.

radioactive decay
  تباهی ِ پرتو-ژیرا   
tabâhi-ye partow-žirâ

Fr.: désintégration radioactive   

Spontaneous emission by a nucleus of photons or particles.

radioactive; → decay.

radioactive isotope
  ایزوتوپ ِ پرتو-ژیرا   
izotop-e partow-žirâ

Fr.: isotope radioactif   

A → nuclide that is radioactive.

radioactive; → isotope.

radioactive nuclide
  هسته‌وار ِ پرتو-ژیرا   
hastevâr-e partowžirâ

Fr.: nucléide radioactif   

A → nuclide that disintegrates by emitting radiation and transforms into another nuclide. Same as → radionuclide.

radioactive; → nuclide.

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