An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 602
Iron Age
  عصر ِ آهن   
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; → age.

iron convection zone (FeCZ)
  زنار ِ همبز ِ آهن   
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).

iron; → convection; → zone.

iron core
  مغزه‌ی ِ آهن   
maqze-ye âhan

Fr.: cœur de fer   

1) Electromagnetism: A bar of → soft iron that passes through a coil and serves to increase the → inductance of the coil.
2) The innermost part of some planets, such as Mercury, Venus, and Earth, which have a molten iron-rich core.
3) The end point in the evolution of stars with a mass above ~ 10 → solar masses. Such a star evolves in several stages over millions of years during which various → thermonuclear reactions take place in the star core. Each stage results in a core composed of heavier elements. The process ends when → silicon burning produces a core of iron-nickel. Since iron has the maximum → binding energy per → nucleon, the → nuclear fusion cannot proceed further. The iron core shrinks and heats up. It is maintained against → gravitational collapse by → electron degeneracy pressure, but it continues to grow as Si burning adds more iron. When the core reaches its → Chandrasekhar limit, it becomes unstable and undergoes the → core collapse.

iron; → core.

iron meteorite
  شخانه‌ی ِ آهنی   
šaxâne-ye âhani (#)

Fr.: météorite ferreux   

A meteorite which is composed mainly of iron mixed with smaller amounts of → nickel. Iron meteorites make up about 4.4% of all meteorites. See also → stony meteorite, → stony-iron meteorite.

iron; → meteorite.

iron opacity peak
  ستیغ ِ کدری ِ آهن   
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).

iron; → opacity; → peak.

iron peak
  ستیغ ِ آهن   
setiq-e âhan

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.

iron peak element
  بن‌پار ِ ستیغ ِ آهن   
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).

iron; → peak; → element.


Fr.: ironique   

1) Using words to convey a meaning that is the opposite of its literal meaning; containing or exemplifying irony: an ironic novel; an ironic remark.
2) Of, pertaining to, or tending to use irony or mockery; ironical (

irony; → -ic.

govâžé (#)

Fr.: 1) ironie; 2) ironiser   

1) The humorous or mildly sarcastic use of words to imply the opposite of what they normally mean. → ironic.
2) An instance of this, used to draw attention to some incongruity or irrationality (

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
  کهکشان ِ بی‌سامان ِ گونه‌ی ِ I   
kahkašân-e bisâmân-e gune-ye I

Fr.: galaxie irrégulière de type I   

An → irregular galaxy that shows a hint of a spiral arm or bar, and can be placed at the far end of spirals in the → Hubble sequence.

irregular; → galaxy.

Irr II galaxy
  کهکشان ِ بی‌سامان ِ گونه‌ی ِ II   
kahkašân-e bisâmân-e gune-ye I

Fr.: galaxie irrégulière de type II   

An amorphous, → irregular galaxy that does not appear to show any structure that can place it into the → Hubble sequence.

irregular; → galaxy.


Fr.: éclairement énergétique   

The → energy at all → wavelengths that is incident on unit area of surface in unit time. It is measured in Watts per square meter.

Irradiance, from ir- variant of → in- (by assimilation) before r + radi(ant), → radiation, + -ance a suffix used to form nouns either from adjectives in -ant or from verbs.

Tâbešdâri, from tâbeš, → radiation, + dâri, verbal noun from dâštan "to have, hold," → property.

  تابش دادن   
tâbeš dâdan

Fr.: irradier   

To expose something to → radiation.


Tâbeš, → radiation, dâdan "to give," → irradiation.

  ۱) تابش‌دهی، تابش‌گیری؛ ۲) نورگسترد   
1) tâbešdehi, tâbešgiri; 2) nurgostard

Fr.: irradiation   

1) Exposure to any kind of radiation or atomic particles.
2) An optical effect that makes a bright object appear larger than it really is when viewed against a darker background.

Irradiation, from ir- variant of → in- (by assimilation) before r + → radiation.

1) Tâbešdehi, tâbešgiri;, from tâbešradiation + 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").
2) Nurgostard, from nur, → light, + gostard past stem of gostardan "to expand; to spread; to diffuse" (Mid.Pers. wistardan "to extend; to spread;" Proto-Iranian *; Av. vi- "apart, away from, out" (O.Pers. viy- "apart, away;" cf. Skt. vi- "apart, asunder, away, out;" L. vitare "to avoid, turn aside") + Av. star- "to spread," starati "spreads;" cf. Skt. star- "to spread out, extend, strew," strnati "spreads;" Gk. stornumi "I spread out," strotos "spread, laid out;" L. sternere "to spread;" Ger. Strahlung "radiation," from strahlen "to radiate," from Strahl "ray;" from M.H.G. strāle; from O.H.G. strāla "arrow," stripe; PIE base *ster- "to spread").

irrational number
  عدد ِ ناوابری   
adad-e nâvâbari

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.

From ir- a prefix meaning "not," a variant of → in-, + → rational; → number.

  ۱) بی‌سامان؛ ۲) نارزن‌مند   
1) bisâmân (#); 2) nârazan-mand

Fr.: irrégulier   

1) Lacking symmetry, even shape, formal arrangement, etc. → irregular galaxy; → irregular variable.
2) Not according to rule, or to the accepted principle, method, course, order, etc.

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."

irregular galaxy
  کهکشان ِ بی‌سامان   
kahkašân-e bisâmân

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.

irregular; → galaxy.

irregular satellite
  بنده‌وار ِ بی‌سامان، ماه ِ ~   
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.

irregular; → satellite.

irregular variable
  ورتنده‌ی ِ بی‌سامان   
vartande-ye bisâmân

Fr.: variable irrégulière   

A type of variable star in which variations in brightness show no regular periodicity. There are two main types, irregular eruptive variables and irregular pulsating variables.

irregular; → variable.

vâgaštnâpazir (#)

Fr.: irréversible   

Not capable of returning to an original condition. → irreversible process.

Irreversible, from ir- "not," variant of → in- + → reversible.

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