An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 13116 Search : far
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) mile (#)

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) → stellar bar, → 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) Mile, 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.

Barnard's loop
  گردال ِ بارنارد   
gerdâl-e Bârnârd

Fr.: boucle de Barnard   

A very faint nebular shell of huge size enveloping the central portion of Orion.

Named after → Barnard, who discovered the loop in 1895; → loop.

Barnard's star
  ستاره‌ی ِ بارنارد   
setâre-ye Bârnârd

Fr.: étoile de Barnard   

A → red dwarf in the constellation → Ophiuchus discovered in 1916 by E.E. Barnard, that until 1968 had the largest → proper motion of any star. It moves on the sky 10.3 arcseconds per year, which means that it travels the equivalent of a lunar diameter every 180 years. It is the second nearest star system to the Sun.

In honor of → Barnard; → star.

<< < -es -iv -ti 21 a p abe abs abs aca acc acc acr act ada adh Adr aer aga air Alf Alg alk Alp alt alu amm ana And ang ani ano ant ant Ap apo app app Aqu Arc arg arr asc ass ast ast asy atm ato att aur aut axi B-m bad Bal bar bar Bay Bed ber Bet bif bim bin bio bis bla ble blu Bod Bol bor bou Bra Bre bro bul C-t Cal Cam can car Car Cas cat cav cel cen cer Cha cha Cha che chl Cir cir cir Cla cli clo clu co- coc coh col col col Com com com com com com com com Com con con con con con con con con con con con con coo Cor Cor cor cos cos cos Cou cou Cra Cre cri cro cub cur cyc cyl Dan dat Dav de- Deb dec dec dee def deg del Den den der det deu dew dic dif dif dil Dip dir dis dis dis dis dis diu dod Dop dou Dra dua dus dwa dyn DZ Ear ecc eco edi EHB Ein ela ele ele ele ele ell eme emp end Eng ent epi equ equ era ESP eth Eur evi exa exc exe exi exp exp ext ext ext fac fal far fec Fer fer fie fin fir fis fla Flo flu fog for for Fou fra fre fre Fro fun G s Gal gal gal Gar gau geg gen geo geo geo ger gla gly gra gra gra gra gra Gre gro GYR Had Hal hap Har HD hea hel hel Hen Her hex hig Hil hol Hoo hor hou Hub hum hyb hyd hyd hyp hys ide ign ima imp imp in- inc Ind ind ine inf inf inf ini ins ins ins int int int int Int int int int inv ion iri irr iso iso iso Jea Jor jum K c Kep Ker kin kno lab Lam Lan Lap las lat Le lef len lev lig lig lin lin lin liq Lit loc log lon lou LS lun lun Lym M s Mag mag mag mag mag mag maj man Mar mas mas mat May mea mec mel mer mes met met met mic mid mil Min Mir mix mod mod mol mon mor mov mul mur mys nan nat nav nec Nep neu New New NGC nob nom non non nor nos nuc nuc num nut obj obl obs occ oct off oli oni ope opp opt opt orb ord org orp osc out ove oxi P-w pal par par par par Pas pat pej per per per per per per pha Phe pho pho pho phy pin pla Pla pla pla pla plu poi pol pol Pol pol por pos pot Poy pre pre pre pre pri pri pri pro pro pro pro pro pro Psa pul pum Q i qua qua qua qua R A rad rad rad rad rad rad Ram Ran rat rea rea rec rec red red ref ref reg rei rel rel rem rep res res res ret rev Rho Rie ril riv rog Ros rot rul S A Sag sam sat sca sca Sch Sco Sec sec sec seg sel sem sen set Sha sha shi sho sid sig sim sin Sir ske sli Smo soc sof sol sol sol sol sou sou spa spe spe Spe spe sph spi Spi spr sta sta sta sta sta ste ste ste Sto str str sub sub sub suc sun sup sup sup sup sur swa syn syn tac tas tel tem ter tes the the the the thi thr tid til tip ton tor tou tra tra tra tra Tri tri tru tsu tur two Typ UHE ult unc uni uni uni upg ura uti val var vec Vel ver Ver vie Vir vis vis vol W-R war wav wav wea Wei wha wid win WN3 Wol wri xen yok zen zij > >>