An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



<< < "sh ADa adi adv bad Che de ene gra inf loa ove qua rad rad rad rad rad rad rea SIM the > >>

Number of Results: 435 Search : ad
  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.

radio flux density
  چگالی ِ شار ِ رادیویی   
cagâli-ye šârr-e râdioyi

Fr.: densité de flux radio   

The flux of → radio waves that falls on a → detector per → unit → surface area of the detector per unit → bandwidth of the radiation per unit → time. The unit is → jansky.

radio; → flux; → density.

radio frequency
  بسامد ِ رادیویی   
basâmad-e râdio-yi (#)

Fr.: fréquence radio   

The → electromagnetic radiation with the frequency range between 3 → kiloherz (kHz) to 300 → gigahertz (GHz). See also → radio wave.

radio; → frequency.

radio galaxy
  رادیو-کهکشان، کهکشان ِ رادیویی   
râdio kahkešân, kahkešân-e râdioyi

Fr.: radiogalaxie   

A galaxy that is extremely luminous at radio wavelengths between 10 MHz and 100 GHz. The radio luminosity of a strong radio galaxy (1037-1039 watts) can be up to a million times greater than the radio output of an ordinary galaxy and up to a hundred times greater than the optical luminosity of a galaxy such as the Milky Way. The optical counterparts of radio galaxies are usually an → elliptical galaxy. Radio galaxies often exhibit jet structure from a compact nucleus. They typically display two → radio lobes that are often approximately aligned with the jets observed in the optical and that may extend for millions of → light-years.

radio; → galaxy.

radio interferometer
  اندرزنش‌سنج ِ رادیویی   
andarzanešsanj-e râdioyi

Fr.: interféromètre radio   

An → interferometer designed for radio frequencies.

radio; → interferometer.

radio jet
  رادیو-شان، شان ِ رادیویی   
radio-šân, šân-e râdioyi

Fr.: jet radio   

An → astrophysical jet appearing in the radio wavelengths of the electromagnetic spectrum.

radio; → jet.

radio lobe
  لپ ِ رادیویی   
lap-e râdioyi

Fr.: lobe radio   

An extended region of diffuse radio emission, often dumbbell shaped, that surrounds a radio galaxy.

radio; → lobe.

radio noise
  نوفه‌ی ِ رادیویی   
nufe-ye râdioyi (#)

Fr.: bruit radio   

The electromagnetic noise at radio wavelengths.

radio + → noise.

radio pulsar
  رادیو-تپار، پولسار ِ رادیویی   
râdio-tapâr, pulsâr-e râdio-yi

Fr.: pulsar radio   

A → pulsar that emits → pulses in → radio waves. The bulk of discovered pulsars are radio pulsars. There is a small number of pulsars that emit at optical wavelengths, X-ray wavelengths, and gamma-ray wavelengths.

radio; → pulsar.

<< < "sh ADa adi adv bad Che de ene gra inf loa ove qua rad rad rad rad rad rad rea SIM the > >>