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: 482
beam
  تابه   
tâbé (#)

Fr.: 1) faisceau, 2) lobe, 3) tache de diffraction   

1) A collection of nearly parallel → light  → rays or a concentrated stream of → particles. See also → beam of light.
2) The area of the sky being observed at any one time by a → radio telescope.
3) The size of the → diffraction pattern; synonymous with point spread function.

M.E. beem, from O.E. beam "tree;" akin to O.H.G boum "tree," Ger. Baum.

Tâbé, from tâb; tâbidan "light; to shine" + noun suffix.

beam efficiency
  کار‌آیی ِ تابه   
kârâi-ye tâbé

Fr.: efficacité de lobe   

A parameter indicating the quality of an antenna as a direction measuring device. It is given by the ratio of the total received power contained in the main beam of an antenna to the total power (including the sidelobes); the same as main beam efficiency. See also → beamwidth.

beam; → efficiency.

beam of light
  تابه‌ی ِ نور   
tâbe-ye nur (#)

Fr.: faisceau lumineux   

A relatively large bundle of → rays of light. See also → pencil of light.

beam; → light.

beam of particles
  تابه‌ی ِ ذره   
tâbe-ye zarré

Fr.: faisceau de particules   

A narrow unidirectional flow of particles

beam; → particle.

beam splitter
  فاقگر ِ تابه   
fâqgar-e tâbé

Fr.: lame séparatrice   

A partially reflecting mirror which permits a part of the light beam to pass through and reflects the rest.

beam; splitter, from to split, from M.Du. splitten, from P.Gmc. *spl(e)it-, PIE *(s)plei- "to split, splice."

Fâqgar, from fâq "split, breach, division" + tâbébeam.

beam switching
  دگربانی ِ تابه   
degarbâni-ye tâbé

Fr.: permutation de lobe   

In single dish radio astronomy, any technique which forms the difference of signals received from two (or more) pointings on the sky without physically moving the main reflector of the antenna. By rapidly forming differences between sky positions that do and do not contain astronomical sources, beam switching can minimize the corruption of spectral baselines by non-idealities in the instrumental frequency response, or of continuum observations by atmospheric fluctuations.

beam; → switching.

beamwidth
  تابه-پهنا   
tâbe-pahnâ

Fr.: largeur de lobe   

The angle between the two directions in the main beam at which the power response has fallen to half its maximum value. → beam efficiency.

From → beam + → width.

Tâbe-pahnâ, from tâbé, → beam, + pahnâ "width," → broad.

beat
  زنش   
zaneš (#)

Fr.: battement   

The periodic and alternatively strengthening and weakening of two waves of similar frequencies when they interfere with one another. In particular, the soft and loud sounds created by the interference of two sound waves of similar frequencies.

M.E. beten, from O.E. beaten, from P.Gmc. *bautan; IER *bhau- "to strike."

Zaneš, noun from zan- present tense stem of zadan "to beat, strike" + verbal noun suffix. Zadan from Mid.Pers. zatan, žatan; O.Pers./Av. jan-, gan- "to strike, hit, smite, kill" (jantar- "smiter"); cf. Skt. han- "to strike, beat" (hantar- "smiter, killer"); Gk. theinein "to strike;" L. fendere "to strike, push;" Gmc. *gundjo "war, battle;" PIE *gwhen- "to strike, kill."

beat Cepheid
  کِفِیءوسی ِ زنشی   
kefeusi-ye zaneši

Fr.: céphéide à battement   

A Cepheid variable in which two or more almost identical periods of variability pass into and out of phase with each other, producing periodic amplitude fluctuations in their light curves. Beat periods are typically about 2 hours.

beat; → Cepheid.

Beaufort scale
  مرپل ِ بوفورت   
marpel-e Beaufort

Fr.: échelle de Beaufort   

A system for estimating and reporting wind speeds which has 13 standardized categories and associated descriptions. The Beaufort scale ranges from 0 for complete calm to 12 for a cyclone. In this scale, the wind speed (in km/h) equals 3B1.5, where B is the Beaufort number of the wind. The scale was originally devised for use at sea but has subsequently been modified for use over land.

Named after Admiral Sir Francis Beaufort (1774-1857), who introduced the first version of the system in 1805; → scale.

beauty
  زیبایی   
zibâyi (#)

Fr.: beauté   

A combination of qualities that pleases the mind.

M.E. be(a)ute, from O.Fr. beautez, beltet "beauty, seductiveness, beautiful person" from V.L. bellitatem (nominative bellitas) "state of being handsome," from L. bellus "pretty, charming."

Zibâyi, from zibâ "beautiful," related to zib "beauty, elegance, ornament," zibidan "to suit, to adorn."

because
  زیرا   
zirâ (#)

Fr.: parce que   

For the reason that; on account of.

M.E. bi cause "by cause," from O.E. bi "by" (akin to Du. bij, O.H.G. bi, Ger. bei, Goth. bi) + → cause.

Zirâ, variants azirâ, zirâk, azirâk, from Mid.Pers. êt rây cê or ê(t) râd cê "because," literally "this reason why;" from êd "this" (O.Pers. aita; Av. aēta "this;" cf. Skt. etá); rây, → reason; "what" (O.Pers/Av. ci- "what, any," collateral stem to ka- "who?, what?;" cf. Skt. ka-; Gk. po-; L. quo-; E. what, who; PIE *qwos/*qwes).

Becklin-Neugebauer object
  بر‌آخت ِ بکلین-نیوجباؤر   
barâxt-e Becklin-Neugebauer

Fr.: objet de Becklin-Neugebauer   

A compact infrared source in the Orion molecular cloud (OMC-1). It is thought to be a very dusty compact H II region surrounding a young B0 or B1 star.

After Eric Becklin (1940-), and Gerry Neugebauer (1932-) who discovered the object in 1967; → object.

become
  شدن   
šodan (#)

Fr.: devenir   

To come, change, or grow to be.

M.E. becumen; O.E. becuman "happen, come about," also "meet with, arrive;" akin to Du. bekomen, O.H.G. biqueman "obtain," Ger. bekommen, Goth. biquiman; from be- a prefix denoting several meanings, and → come.

Šodan "to become, to go, to pass, to change," from Mid.Pers. šudan, šaw- "to go;" Av. š(ii)auu-, šiyav- "to move, go," šiyavati "goes," šyaoθna- "activity; action; doing, working;" O.Pers. šiyav- "to go forth, set," ašiyavam "I set forth;" cf. Skt. cyu- "to move to and fro, shake about; to stir," cyávate "stirs himself, goes;" Gk. kinein "to move;" Goth. haitan "call, be called;" O.E. hatan "command, call;" PIE base *kei- "to move to and fro."

becquerel
  بکرل   
becquerel (#)

Fr.: becquerel   

The → SI unit of → radioactivity. One becquerel corresponds to the → disintegration of one atom per second. Abbreviation: Bq. → curie.

Named for the French physicist Henri Becquerel (1852-1908), who discovered radioactivity in 1896.

bedrock
  سنگ‌بستر   
sangbastar (#)

Fr.: socle   

Solid → rock present beneath any → soil, → sediment, or other surface cover. In some locations it may be exposed at earth's surface.

Bedrock, from bed (O.E. bed, from P.Gmc. *badjam "sleeping place dug in the ground;" PIE *bhedh- "to dig, pierce") + → rock.

Sangbastar, from sang "stone, rock," → stone, + bastar "bed" (Mid.Pers. vistarak, cognate with Mod.Pers. gostar "a bed; spreading; scatterer," Av. star-, starəta- "spread," from star- "to spread," Skt. strnâti).

beech
  راش   
râš (#)

Fr.: hêtre   

Any tree of the genus Fagus, especially Fagus sylvatica of Europe, having smooth grayish bark. In Iran Fagus orientalis populates Caspian highland forests from Âstârâ to Gorgân.

M.E. beche, from O.E. becew; cf. Dutch beuk, Ger. Buche, from PIE root *bhagos "beech tree;" also cf. Gk. phegos "oak," L. fagus "beech," Rus. buzina "elder."

Râš, as named in Gilân, Râmsar, Šahsavâr, Kalârdašt. Its other names: (Mâzandarân) mers, (Ammaârlu, Manjil) râj, (Tevâleš, Mt. Dorfak) aluš, alâš, âlâš, (Nur) celer, celar (Iranica).

Beehive Cluster
  خوشه‌ی ِ کندو   
xuše-ye kandu

Fr.: amas de la ruche   

Praesepe.

behavior
  رفتار   
raftâr (#)

Fr.: comportement   

Manner of behaving or acting.

M.E. behavour, from behaven "to behave," altered by model havour, from O.Fr. avoir "to have."

Raftâr "behavior, walking, going," from raft past tense stem of raftan "to go, walk, proceed" (present tense stem row-, Mid.Pers. raftan, raw-, Proto-Iranian *rab/f- "to go; to attack") + -âr prefix forming action noun.

Bekenstein formula
  دیسول ِ بکنشتاین   
disul-e Bekenstein

Fr.: formule de Bekenstein   

The mathematical expression giving the → entropy, S, of a → black hole as a function of the area of its → event horizon, A: S = (kc3A)/(4Għ), where k is → Boltzmann's constant, ħ is the → reduced Planck's constant, and G the → gravitational constant. It can also be expressed by S = (kA)/(4lP2), where lP is the → Planck length. The existence of this entropy led to the prediction of the → Hawking radiation, because an entropy is associated with a temperature and a temperature to a → thermal radiation. The entropy of a black hole increases continuously because the fall of material into it increases its area.

For Jacob D. Bekenstein (1947-), an Israeli theoretical physicist, who contributed to the foundation of black hole thermodynamics; → formula.

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