miyânband-e titaki, ~ titakvâr
Fr.: diaphragme iris
A mechanical device, consisting of thin overlapping plates, designed to smoothly vary the effective diameter of a lens, thereby controlling the amount of light allowed through.
A metallic → chemical element occurring abundantly in
combined forms and used alloyed in a wide range of important tools and structural materials;
→ Atomic number 26;
→ atomic weight 55.845;
→ melting point about 1,535°C;
→ boiling point about 2,750°C;
→ specific gravity 7.87 at 20°C;
→ valence +2, +3, +4, or +6.
Iron is of critical importance to life, i.e. plants, humans, and animals. It occurs in
hemoglobin, a molecule that carries → oxygen
from the lungs to the tissues and then transports
→ carbon dioxide (CO2) back from the tissues
to the lungs.
Iron, from O.E. isærn, from P.Gmc. *isarnan
(cf. O.S. isarn, O.N. isarn, M.Du. iser, O.H.G. isarn,
Ger. Eisen) "holy metal" or "strong metal," probably
an early borrowing of Celt. *isarnon (cf. O.Ir. iarn, Welsh haiarn),
from PIE *is-(e)ro- "powerful, holy," from PIE *eis "strong"
(cf. Skt. isirah "vigorous, strong," Gk. ieros "strong").
Âhan, Kurd. âsan, Mid.Pers. âhan; Av. aiianhaēna- "made of metal," from aiiah- "metal;" cf. Skt. áyas- "iron, metal;" L. aes "brass;" Goth. aiz "bronze;" O.H.G. ēr "ore" (Ger. Erz "oar"); O.E. ora "ore, unworked metal," ar "brass, copper, bronze."
asr-e âhan (#)
Fr.: âge du fer
The period generally occurring after the → Bronze Age, marked by the widespread use of iron. Its date and context vary depending on the country or geographical region. The Indo-European Hittites are the first people to work iron, in the Asia Minor, from about 1500 BC.
iron convection zone (FeCZ)
zonâr-e hambaz-e âhan
Fr.: zone convective du fer
A → convective zone close to the surface of → hot stars caused by a peak in the → opacity due to iron recombination. A physical connection may exist between → microturbulence in hot star atmospheres and a subsurface FeCZ. The strength of the FeCZ is predicted to increase with → metallicity and → luminosity, but decrease with → effective temperature. The FeCZ in hot stars might also produce localized surface magnetic fields. The consequence of the FeCZ might be strongest in → Wolf-Rayet stars. These stars are so hot that the → iron opacity peak, and therefore FeCZ, can be directly at the stellar surface or, better said, at the → sonic point of the wind flow. This may relate to the very strong → clumping found observationally in Wolf-Rayet winds, and may be required for an understanding of the very high → mass loss rates of Wolf-Rayet stars (See Cantiello et al. 2009, A&A 499, 279).
Fr.: cœur de fer
1) Electromagnetism: A bar of → soft iron that passes
through a coil and serves to increase the → inductance of
šaxâne-ye âhani (#)
Fr.: météorite ferreux
iron opacity peak
setiq-e kederi-ye âhan
Fr.: pic d'opacité du fer
A bump appearing in the plot of stellar → opacity versus temperature. The ionization of the heaviest → chemical elements, especially → iron, which is the most abundant heavy metal, produces a large number of weak spectral → absorption lines. These lines dominate the stellar opacity in the temperature range 105-106 K and furnish two local opacity peaks: a large peak around 2 × 105 K and a smaller one around 1.5 × 106 K (Rogers & Iglesias, 1992, ApJS 79, 507; Iglesias et al. 1992, ApJ, 397, 717).
Fr.: pic du fer
A maximum on the element-abundance curve in the vicinity of the iron → atomic number 26. The relative higher abundance of the → iron peak elements results from their being the end products of → nucleosynthesis in the interiors of → massive stars.
iron peak element
bonpâr-e setiq-e âhan
Fr.: élémént du pic du fer
A member of a group of elements with → atomic masses A about 40 to 60 that are synthesized by the → silicon burning process and appear in the → iron peak. They are mainly: → titanium (Ti), → chromium (Cr), → manganese (Mn), → iron (Fe), → cobalt (Co), and → nickel (Ni).
1) Using words to convey a meaning that is the opposite of its
literal meaning; containing or exemplifying irony: an ironic novel; an
Fr.: 1) ironie; 2) ironiser
1) The humorous or mildly sarcastic use of words to imply the opposite
of what they normally mean. → ironic.
From L. ironia, from Gk. eironeia "dissimulation, assumed ignorance," from eiron "dissembler," perhaps related to eirein "to speak."
Govâžé, ultimately from Proto-Ir. *ui-vac-, from *ui- prefix denoting "apart, away, out," cf. Av. vi-, O.Pers. viy-, Skt. vi- (Mod.Pers., e.g., gozidan, → select, gozaštan "to cross," → passage) + *uac- "to say, speak," → word; also govâžidan "to make irony of, to say ironically."
Irr I galaxy
kahkašân-e bisâmân-e gune-ye I
Fr.: galaxie irrégulière de type I
Irr II galaxy
kahkašân-e bisâmân-e gune-ye I
Fr.: galaxie irrégulière de type II
Fr.: éclairement énergétique
To expose something to → radiation.
1) tâbešdehi, tâbešgiri; 2) nurgostard
1) Exposure to any kind of radiation or atomic particles.
1) Tâbešdehi, tâbešgiri;, from tâbeš→ radiation + giri verbal noun of gereftan
"to take, seize" (Mid.Pers. griftan, Av./O.Pers. grab- "to take, seize," cf.
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;"
PIE base *ghrebh- "to seize"); dahi verbal noun of dâdan
"to give," Mid.Pers. dâdan "to give" (O.Pers./Av. dā- "to give, grant, yield,"
dadāiti "he gives;" Skt. dadáti "he gives;"
Gk. tithenai "to place, put, set," didomi "I give;"
L. dare "to give, offer," facere "to do, to make;"
Rus. delat' "to do;" O.H.G. tuon, Ger. tun,
O.E. don "to do;" PIE base *dhe- "to put, to do").
Fr.: nombre irrationnel
A → real number which cannot be exactly expressed as a ratio a/b of two integers. Irrational numbers have decimal expansions that neither terminate nor become periodic. Every → transcendental number is irrational. The most famous irrational number is √ 2.
1) bisâmân (#); 2) nârazan-mand
From O.Fr. irregulier, from M.L. irregularis, from → in- "not" + L. regularis from regula "rule," from PIE *reg- "move in a straight line," hence, "to direct, rule" (cf. Pers. râst "right, straight;" O.Pers. rāsta- "straight, true," rās- "to be right, straight, true;" Av. rāz- "to direct, put in line, set," razan- "order;" Skt. raj- "to direct, stretch," rjuyant- "walking straight;" Gk. orektos "stretched out;" L. regere "to lead straight, guide, rule," p.p. rectus "right, straight;" Ger. recht; E. right).
Bisâmân, from bi- "not, without" + sâmân "order, arrangement, disposition; boundary, limit," Lârestâni sâmon "sign or mark separating one field from another," Gilaki, Tabari šalmân "a straight peace of wood or beam, post;" Mid.Pers. sâmânak, sahmân "limit;" loaned into Arm. sahmân; cf. Skt. sīmān-, sīmā- "boundary, border, limit."
Fr.: galaxie irrégulière
A galaxy with no spiral structure and no symmetric shape. Irregular galaxies are usually filamentary or very clumpy in shape and tend to smaller than others. Two types of irregular galaxies are defined, → Irr I galaxy and → Irr II galaxy.
bandevâr-e bisâmân, mâh-e ~
Fr.: satellite irrégulier
A satellite whose orbit around its planet is eccentric, inclined with respect to the equatorial plane, and relatively far from the planet. Strong solar perturbations cause the orbit to precess. → regular satellite.