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: 479
Balmer continuum
  پیوستار ِ بالمر   
peyvastâr-e Bâlmer

Fr.: continuum de Balmer   

A continuous range of wavelengths in the Balmer spectrum of hydrogen corresponding to transitions between the energy levels n = 2 and n = .

Balmer; → continuum.

Balmer decrement
  کاهه‌ی ِ بالمر   
kâhe-ye Bâlmer

Fr.: décrément de Balmer   

The intensity ratio among the couple of relatively adjacent → Balmer lines, for example Hα/Hβ and Hβ/Hγ, which have well-known theoretical values. They are used to determine the → interstellar extinction.

Balmer; → decrement.

Balmer discontinuity
  ناپیوستگی ِ بالمر   
nâpeyvastegi-ye Bâlmer

Fr.: discontinuité de Balmer   

An abrupt decrease in the intensity of the continuum at the limit of the → Balmer series of hydrogen (at about 3650 Å), caused by the energy absorbed when electrons originally in the second → energy level are ionized. Same as → Balmer jump.

Balmer; → discontinuity.

Balmer formula
  دیسول ِ بالمر   
disul-e Bâlmer

Fr.: formule de Balmer   

A special solution of the mathematical formula which represents the wavelengths of the various spectral series of hydrogen in which the lower energy level is n = 2.

Balmer; → formula.

Balmer jump
  جهش ِ بالمر   
jaheš-e Bâlmer

Fr.: saut de Balmer   

Same as → Balmer discontinuity.

Balmer; → jump.

Balmer limit
  حد ِ بالمر   
hadd-e Bâlmer

Fr.: limite de Balmer   

The wavelength in the blue end of the → Balmer series, at 3646 Å, near which the separation between successive lines decreases and approaches a → continuum.

Balmer; → limit.

Balmer line
  خط ِ بالمر   
xatt-e Bâlmer

Fr.: raies de Balmer   

The → spectral lines making up the → Balmer series.

Balmer; → line.

Balmer series
  سری ِ بالمر   
seri-ye Bâlmer (#)

Fr.: série de Balmer   

A series of hydrogen → spectral lines (Hα, Hβ, Hγ, and others) that lies in the visible portion of the spectrum and results when electrons from upper → energy levels (n > 2) undergo → transition to n = 2.
Historically, Balmer emission lines (mainly Hα) from ionized nebulae were first observed by O. Struve and C. T. Elvey (1938, ApJ 88, 364). This was an important indication of the existence of hydrogen, in the ionized state, in the → interstellar medium.

Balmer; → series.

band
  باند   
bând (#)

Fr.: bande   

General:1) A strip serving to encircle and bind one object or to hold a number of objects together. 2) A strip or stripe that contrasts with something else in color, texture, or material.
Physics: 1) A specific range of wavelengths or frequencies of electromagnetic radiation.
2) Closely packed spectral lines that appear to form a continuous group. → absorption band; → emission band.

From M.E. bende, O.E. bend, from O.Fr. bande, bende, P.Gmc. *bindan, from PIE *bendh- "to bind" (cf. Goth bandi "that which binds;" Av./O.Pers. band- "to bind, fetter," banda- "band, tie," Skt. bandh- "to bind, tie, fasten," bandhah "a tying, bandage."

Bând, adoption from E. band, which is cognate and synonymous with Pers. band, present tense stem of bastan "to bind, shut," Mid.Pers. bastan, band, Av./O.Pers. band-, as explained above. See also → strip.

band head
  باندسر، سر ِ باند   
bândsar, sar-e bând

Fr.: tête de bande   

A location on the spectrogram of a molecule at which the lines of a band stack.

Band head, from → band + head, from O.E. heafod "top of the body," also "upper end of a slope," also "chief person, leader," from P.Gmc. *khaubuthan, from PIE *kauput- "head" (cf. Skt. kaput-, L. caput "head," Lori kapu "head," kapulek "skull, middle of the head").

Bândsar, from → bând + sar "head," soru, sorun "horn," karnâ "a trumpet-like wind instrument" (originally made from animal horns), variant sornâ "a wind instrument;" Mid.Pers. sar "head," sru "horn;" Av. sarah- "head," srū- "horn, nail;" cf. Skt. śiras- "head, chief;" Gk. kara "head," karena "head, top," keras "horn;" L. cornu "horn," cerebrum "brain;" P.Gmc. *khurnaz (E. horn; Ger. Horn, Du. horen), from PIE *ker- "head, horn."

band spectrum
  بیناب ِ باندی   
binâb-e bândi

Fr.: spectre de bande   

A spectrum which consists of a number of bands each having one sharp edge. Each band is composed of a large number of closely spaced emission or absorption lines. Band spectra are typical of molecules. Bands produced by titanium oxide, zirconium oxide, and carbon compounds are characteristic of low temperature stars.

Band spectrum, from → band + → spectrum.

Binâb-e bândi, from binâb, → spectrum + bândi, relating to bând, → band.

band-pass
  گذر-باند   
gozar-bând

Fr.: bande passante   

A range of frequencies that can pass through a filter such as one in an electrical circuit.

From → band + pass, from O.Fr. passer, from V.L. *passare "to step, walk, pass," from L. passus "step, pace;" cf. Pers. "foot," pey "step."

Gozar-bând, from gozar "passage, transit, passing," gozaštan "to pass, cross, transit," from Mid.Pers. vitârtan + bând, → band.

bandpass filter
  پالایه‌ی ِ گذر-باند   
pâlâye-ye gozar-bând

Fr.: filtre de bande   

An electric filter that transmits a known band of frequencies but suppresses unwanted frequencies above and below this band.

bandpass; → filter.

bandwidth
  باند-پهنا   
bândpahnâ

Fr.: largeur de bande   

The portion of the electromagnetic spectrum that is permitted to pass through an electronic device, such as a radio telescope detector. The term refers to either a wavelength interval or a frequency interval.

Bandwidth, from → band + → width.

Bândpahnâ, from bând, → band, + pahnâ, → width, from pahn "wide," → broad.

bar
  ۱) بار؛ ۲) میله   
1) bâr (#); 2) milé (#)

Fr.: 1) bar; 2) barre   

1) A unit of → pressure, not belonging to the → International System (SI), equivalent to 106dynes per cm2 and 0.987 → atmospheres.
2) A bar-shaped accumulation of stars in galaxies, created by → density waves in a → spiral galaxy. → galactic bar, → barred spiral galaxy.

1) From Gk. baros "weight," cf. Skt guru, L. gravis; PIE *gwere- "heavy;" cf. Pers. bâr "weight," gerân "heavy," L. brutus "heavy, dull, stupid, brutish," Skt. bhara- "burden, load," bharati "he carries;" PIE *bher- "carry, give birth."
2) From O.Fr. barre, from V.L. *barra "bar, barrier," or perhaps from Gaulish *barro "summit."

1) Loan from Fr., as above.
2) Milé, from Ar. mil "any long and narrow piece of metal," + noun suffix.

barium
  باریوم   
bâriyom (#)

Fr.: barium   

A whitish, malleable, metallic → chemical element; symbol Ba. → Atomic number 56; → atomic weight 137.33; → melting point 725°C; → boiling point 1,640°C; → specific gravity 3.5 at 20°C. Barium was discovered by the Swedish pharmacist and chemist Carl Wilhelm Scheele in 1774. It was first isolated by the British chemist Humphry Davy in 1808.

From Mod.L., from Gk. barys "heavy," from the mineral barytes "heavy spar" (BaSO4), in which the element was discovered; cognate with Pers. bâr "weight," → bar.

barium star
  ستاره‌ی ِ باریومی   
setâre-ye bâriyomi

Fr.: étoile à barium   

A type of star, usually G or K → giants, whose spectra show unusually strong absorption lines of → barium, → strontium, and other → s-process elements.

barium; → star.

Barlow lens
  عدسیِ بارلو   
adasi-ye Barlow (#)

Fr.: lentille de Barlow   

A → negative lens placed in a telescope between the → objective and the → ocular. Its diverging action reduces the convergence of the light cone, forming a larger image at a slightly greater distance.

Peter Barlow (1776-1862), English physicist; → lens.

barn
  بارن   
bârn (#)

Fr.: barn   

In nuclear physics, unit of area for measuring the cross-sections of nuclei. 1 barn equals 10-24 sq. cm.

Barn, from O.E. bereærn "barn," lit. "barley house," from bere "barley" + aern "house." The use of barn in nuclear physics comes from the fact that the term denotes also "an unexpectedly large quantity of something." It seems that when physicists were first studying nuclear interactions, they found out that the interaction probabilities, or cross-sections, were far more larger than expected; the nuclei were `as big as a barn'.

Barnard
  بارنارد   
Bârnârd

Fr.: Barnard   

From Edward Emerson Barnard (1857-1923) American astronomer who made several obserational discoveries.

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