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
ionization correction factor (ICF)
  کروند ِ ارشایش ِ یونش   
karvand-e aršâyeš-e yoneš

Fr.: facteur de correction d'ionisation   

A quantity used in studies of → emission nebulae to convert the → ionic abundance of a given chemical element to its total → elemental abundance. The elemental abundance of an element relative to hydrogen is given by the sum of abundances of all its ions. In practice, not all the ionization stages are observed. One must therefore correct for unobserved stages using ICFs. A common way to do this was to rely on → ionization potential considerations. However, → photoionization models show that such simple relations do not necessarily hold. Hence, ICFs based on grids of photoionization models are more reliable. Nevertheless here also care should be taken for several reasons: the atomic physics is not well known yet, the ionization structure of a nebula depends on the spectral energy distribution of the stellar radiation field, which differs from one model to another, and the density structure of real nebulae is more complicated than that of idealized models (see, e.g., Stasińska, 2002, astro-ph/0207500, and references therein).

ionization; → correction; → factor.

ionization energy
  کاروژ ِ یونش   
kâruž-e yoneš

Fr.: énergie d'ionisation   

Same as → ionization potential.

ionization; → energy.

ionization front
  پیشان ِ یونش   
pišân-e yoneš

Fr.: front d'ionisation   

An abrupt discontinuity between an H II region and the molecular cloud in which it has formed. In this transition region interstellar gas changes from a mostly neutral state to a mostly ionized state.

ionization; → front.

ionization parameter
  پارامون ِ یونش   
pârâmun-e yoneš

Fr.: paramètre d'ionisation   

A ratio representing the number of ionizing photons to the number of electrons in a nebular emitting region.

ionization; → parameter.

ionization potential
  توند ِ یونش   
tavande yoneš

Fr.: potentiel d'ionisation   

The energy required to remove an electron from an isolated atom or molecule. The ionization potential for hydrogen is 13.6 eV, which corresponds to an ultraviolet ionizing photon with a wavelength of 912 A. Also called → ionization energy.

ionization; → potential.

ionization stratification
  چینه‌بندی ِ یونش   
cine-bandi-ye yoneš

Fr.: stratification d'ionisation   

The spatial distribution of ionic species around an ionization source according to their → ionization potentials. The higher the ionization potential, the nearer to the source the corresponding ions will be.

ionization; → stratification.

ionization-bounded H II region
  ناحیه‌ی ِ II H‌ی ِ یونش‌کران‌مند   
nâhiye-ye H II-e yoneš-karânmand

Fr.: région H II bornée par ionisation   

An H II region whose → exciting star(s) do not have enough → Lyman continuum photons to ionize the whole region. → density-bounded H II region.

ionization; → bounded; → H II region.

ionize
  یونیدن   
yonidan (#)

Fr.: ioniser   

To change into ions. Verbal form of → ionization.

From → ion + → -ize.

ionized
  یونیده   
yonidé (#)

Fr.: ionisé   

Converted into ions.

P.p. of → ionize.

ionized gas
  گاز ِ یونیده   
gâz-e yonidé (#)

Fr.: gaz ionisé   

A gas composed partially or totally of → ions.

ionized; → gas.

ionized hydrogen region
  ناحیه‌ی ِ هیدروژن ِ یونیده   
nâhiye-ye hidrožen-e yonidé (#)

Fr.: région d'hydrogène ionisé   

Same as → H II region.

ionized; → hydrogen; → region.

ionized nebula
  میغ ِ یونیده   
miq-e yonidé

Fr.: nébuleuse ionisée   

A cloud of matter in the → interstellar medium consisting of → ionized gas, mainly → hydrogen, and → dust. Same as → H II region.

ionized; → nebula.

ionizing radiation
  تابش ِ یوننده   
tâbeš-e yonandé (#)

Fr.: rayonnement ionisant   

A photon that has enough energy to remove an electron from an atom or molecule, thus producing an ion and free electrons.

Ionizing, adj. from → ionize; → radiation.

ionosphere
  یون‌سپهر   
yonsepehr (#)

Fr.: ionosphère   

The region of the Earth's upper atmosphere containing a small percentage of free electrons and ions produced by photoionization of the constituents of the atmosphere by solar ultraviolet radiation.

ion + → sphere.

Iota Orionis
  یوتا-شکارگر، یوتا-اریون،   
Iota-Šekârgar, Iota-Oryon

Fr.: Iota Orionis   

A → multiple star system in the → Orion constellation. Also known as → Hatsya, → Na'ir al-Saif, and HR 1899. It is the brightest star of → Orion's Sword, located at the sword's tip, with an → apparent visual magnitude of 2.8. From parallax measurements, it is located at a distance of roughly 1,330 → light-years (410 parsecs) from the Sun. The system has three components designated Iota Orionis A, B and C. Iota Orionis A is itself a massive spectroscopic binary, with components Iota Orionis Aa and Ab.

Iota, Greek letter ι used in the → Bayer designation of star names; Orionis, genitive of → Orion.

IRAF
     
IRAF

Fr.: IRAF   

A general purpose software package for the reduction and analysis of astronomical data. It is aimed specifically at the reduction of imaging and spectroscopy data obtained using → CCD detector systems. IRAF is developed by the National Optical Astronomy Observatories (NOAO).

Short for Image Reduction and Analysis Facility.

Iranian calendar
  گاهشمار ِ ایرانی   
gâhšomâr-e Irâni (#)

Fr.: calendrier iranien   

The most accurate solar calendar in use, which is based on two successive passages of the Sun through the true vernal equinox. The year length, defined by an ingenious intercalation system devised by the mathematician Omar Khayyâm (A.D. 1048-1131), is 365.2424.. solar days, in perfect agreement with the → vernal-equinox year of 365.24236 solar days (epoch +2000). This interval should not be confounded with the → tropical year of 365.2422 solar days. The most remarkable feature of the calendar is Nowruz, the spring festival, which has its profound roots in the Zoroastrian worldview. Same as → Persian calendar. Click here for more details.

Iranian, of or pertaining to Iran "(land of) the Aryans," as below; → calendar.

Gâhšomâr, → calendar; Irâni adj. of Irân, from Mid.Pers. Êrân "(land of) the Aryans," pluriel of êr "noble, hero," êrîh "nobility, good conduct;" Parthian Mid.Pers. aryân; O.Pers. ariya- "Aryan;" Av. airya- "Aryan;" cf. Skt. ārya- "noble, honorable, respectable."

iridescence
  رنگینستی   
ranginesti

Fr.: iridescence   

The condition or state of being → iridescent; exhibition of colors like those of the → rainbow.

From L. iris (genitive iridis) "rainbow," + → -escence.

iridescent
  رنگینست   
ranginest

Fr.: iridescent   

Producing a display of lustrous, rainbow-like colors.

iridescence

iridium
  ایریدیوم   
iridiom (#)

Fr.: iridium   

A metallic chemical element; symbol Ir. Atomic number 77; atomic weight 192.22; melting point about 2,410°C; boiling point about 4,130°C; specific gravity 22.55 at 20°C. Iridium is a very hard, usually brittle, extremely corrosion-resistant silver-white metal with a face-centered cubic crystalline structure. The unusually high concentration of iridium found in the thin clay layer that marks the boundary between the Cretaceous and Tertiary rocks is attributed to an asteroid impact with Earth 65 million years ago.

Iridium coined 1804 by its discoverer, E. chemist Smithson Tennant (1761-1815) from Gk. → iris "rainbow;" so called for the varying color of its compounds.

<< < -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 > >>