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
GYRE
     
GYRE

Fr.: GYRE   

An open-source (adiabatic/non-adiabatic) pulsation code that calculates the oscillation frequencies of an input stellar model. The code is based on a "Magnus Multiple Shooting" scheme, which is a numerical technique to solve boundary value problems. This is done by subdividing the possible solution space into sub-intervals and solving the pulsation equation in these sub-intervals, assuming continuity conditions. GYRE is integrated into → Modules for Experiments in Stellar Astrophysics (MESA)'s → asteroseismologic module (Townsend & Teitler, 2013, MNRAS 435, 3406).

GYRE, of unknown origin.

gyro-
  لر-   
ler-

Fr.: gyro-   

A combining form meaning "ring, circle, spiral," used in the formation of compound words: → gyroscope, → gyrofrequency, → gyroradius, → gyrate.

From Gk. gyros "circle, ring;" PIE base *geu- "to bend, curve."

From leridan, → gyrate.

gyrofrequency
  لِربسامد   
lerbasâmad

Fr.: fréquence gyromagnétique   

The frequency with which an electron or other charged particle executes spiral gyrations in moving across a magnetic field.

gyro-; → frequency.

gyroradius
  لرشعاع   
leršo'â'

Fr.: gyrorayon   

Same as → Larmor radius.

gyro-; → radius.

gyroscope
  لِرنما، چرخش‌نما   
lernemâ, carxešnemâ

Fr.: gyroscope   

A device for measuring or maintaining orientation. Consisting of a rotating wheel so mounted that its axis can turn freely in certain or all directions, it is based on the principle of conservation of angular momentum. In physics this is also known as gyroscopic inertia or rigidity in space.

Gyroscope, from gyro-, → gyrate + → -scope.

Lernemâ, from ler, → gyrate, + -nemâ-scope; carxešnemâ, from carxešrotation + -nemâ.

GZK cutoff
  بره‌ی ِ گریسن-زاتسپین-کوزمین   
bore-ye Greisen-Zatsepin-Kuzmin

Fr.: limite de Greisen-Zatsepin-Kuzmin   

Same as → Greisen-Zatsepin-Kuzmin cutoff.

Greisen-Zatsepin-Kuzmin cutoff.

H and K lines
  خطهای ِ H و K   
xatthâ-ye H o K

Fr.: raies H et K   

Two prominent → absorption lines, at 3968.5 Å and 3933.7 Å respectively, in the spectra of stars like the → Sun and cooler due to → singly ionized → calcium (Ca II). The strength of H and K lines can be an indication of considerable magnetic activity in the → chromosphere of these stars. The Ca II H and K lines are also common in some kinds of → eruptive variable stars. These lines are not seen in → hot stars, and start to become visible in → A-type stars.

H and K, letters of alphabet, conventionally chosen; → line.

H I
  H I   
H I

Fr.: H I   

Atomic or → neutral hydrogen.

From H, abbreviation of hydrogen + I "one" in Roman number system, nomenclature convention representing neutral atoms.

H I region
  ناحیه‌ی ِ H I   
nâhiye-ye H I

Fr.: région H I   

A region of neutral (atomic) hydrogen in interstellar space. At least 95 percent of interstellar hydrogen is H I. It emits radio waves that are 21 cm long.

H I; → region

H II
  H II   
H II

Fr.: H II   

Ionized → hydrogen, that is a proton nucleus that has lost its unique electron.

From H, abbreviation of hydrogen + II "two" in Roman number system, nomenclature convention representing singly ionized atoms.

H II galaxy
  کهکشان ِ H II   
kahkešân-e H II

Fr.: galaxie H II   

A low-mass and → metal-poor galaxy (1/30-1/3 Zsun), experiencing strong episodes of → star formation, characterized by the presence of bright → emission lines on a faint → blue continuum. The fact that H II galaxies are metal poor and very blue objects seems to suggest that they are young. Nevertheless, several studies show the existence of an → old stellar population underlying the present → star burst in most of these galaxies. This fact indicates that these objects are not young systems forming their first generation of stars. Same as → blue compact dwarf galaxy.
Spectroscopically, H II galaxies are essentially identical to the → giant H II regions found in nearby → irregular and → late-type galaxies. The correlation among structural parameters (→ H-beta → luminosity, → velocity dispersion, → linewidths) and between these parameters and the → chemical composition favors the interpretation of H II galaxies as giant H II regions in distant → dwarf irregular galaxies similar to the ones found nearby. Some examples of H II galaxies are: I Zw 18, SBS 0335-052, II Zw 33, UM 408.

H II; → galaxy.

H II region
  ناحیه‌ی ِ H II   
nâhiye-ye H II

Fr.: région H II   

A type of → emission nebulae composed of very hot gas (about 104 K), mainly ionized hydrogen, created by the ultraviolet radiation of → massive stars. H II regions originate when O or early-type stars, born in → giant molecular clouds, start heating up the cold gas, causing it to become → ionized and "glow". The effective temperatures of the → exciting stars are in the range 3 x 104 to 5 x 104 K, and throughout the nebula hydrogen is ionized. Helium is → singly ionized, and other elements are mostly singly or → doubly ionized. Typical densities in the H II region are of the order 10 to 102 cm-3, ranging as high as 104 cm-3. Internal motions occur in the gas with velocities of order 10 km s-1. The spectra of H II regions are mainly composed of strong → H Irecombination lines and → forbidden lines such as [O III], [O II], [N II]. See also → ionization-bounded H II region; → density-bounded H II region; → compact H II region; → ultracompact H II region.

H II; → region

H II region luminosity
  تابندگی ِ ناحیه‌ی ِ H II   
tâbandegi-ye nâhiye-ye H II

Fr.: luminosité de région H II   

The total number of → Lyman continuum photons emitted by an → H II region. It is usually derived using → radio continuum observations which are less affected by → interstellar extinction. The measured value is often a lower limit because of photon leakage from the H II region and absorption. See also → density-bounded H II region.

H II; → region; → luminosity.

H-alpha
   H-آلفا   
H-âlfâ (#)

Fr.: H-alpha (Hα)   

The → Balmer series spectral line of hydrogen which results from → atomic transition between the → energy levels 2 and 3. It has a wavelength of 656.4 nm and falls in the red region of the visible spectrum.

H, symbol of → hydrogen; alpha (α), the first letter of Gk. alphabet.

H-beta
   H-بتا   
H-betâ (#)

Fr.: H-beta (Hβ)   

The → Balmer series spectral line of hydrogen which results from → atomic transition between the → energy levels 2 and 4. It has a wavelength of 486.1 nm and falls in the → blue region of the → visible spectrum.

H, symbol of → hydrogen; beta (β), the second letter of Gk. alphabet.

H-R diagram
  نمودار ِ H-R   
nemudâr-e H-R

Fr.: diagramme H-R   

Same as → Hertzsprung-Russell diagram.

Short for → Hertzsprung-Russell diagram.

Habing field
  میدان ِ هابینگ   
meydân-e Habing

Fr.: champ de Habing   

A unit used to express the strength of average → far ultraviolet (FUV) intensity in the → interstellar radiation field. It is equal to 1.2 × 10-4 erg cm-2 s-1 sr-1 = 1.6 × 10-3 cm-2 s-1 = 108 photons cm-2 s-1.

Named after Harm Habing, a pioneer in this field (Habing, H. J., 1968, Bull. Astr. Netherlands 19, 421).

habitable
  زیست‌پذیر   
zistpazir

Fr.: habitable   

In → exobiology, having a → temperature range within which → liquid water can exist on the surface of a → planet.

M.E., from O.Fr. habitation, from L. habitare "to live, dwell," frequentative of habere "to have, to hold, possess," from PIE base *ghrebh- "to seize, take, hold, have, give, receive" (cf. Mod.Pers. gereftan "to take, seize;" Mid.Pers. griftan; O.Pers./Av. grab- "to take, seize;" Skt. grah-, grabh- "to seize, take," graha "seizing, holding, perceiving;" M.L.G. grabben "to grab," from P.Gmc. *grab, E. grab "to take or grasp suddenly"); → zone.

Zistpazir, from zist, → life, + pazir "admitting, accepting, having," → -able.

habitable zone (HZ)
  زُنار ِ زیست‌پذیر   
zonâr-e zistpazir

Fr.: zone habitable   

A zone around a → star where the → temperature would be in the range 0-100 °C to sustain → liquid water on the surface of rocky planets (or sufficiently large moons). Water is thought to be a necessary component to the → formation and evolution of Earth-type life. This zone depends on the parent star's luminosity and distance; it will be farther from hotter stars. A more accurate definition of HZ needs to include other factors, such as orbital → eccentricity, heat sources other than stellar irradiation, and atmospheric properties. Same as → circumstellar habitable zone; → ecosphere.

habitable; → zone.

haboob
  هبوب   
habub

Fr.: haboub   

A type of intense dust storm that blows in the deserts of North Africa and Arabia, particularly severe in areas of drought.

Haboob, from Ar. habub (هبوب) "a wind which blows hard and raises the dust."

<< < -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 > >>