An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 446
pâ (#)

Fr.: pied   

1) The terminal part of the vertebrate leg upon which an individual stands.
2) Something resembling a foot in position or use.

M.E., from O.E. fot; cf. O.S. fot, O.N. fotr, Du. voet, O.H.G. fuoz, Ger. Fuß, Goth. fotus "foot;" cognate with Pers. pâ, pây, as below.

"foot;" Mid.Pers. pâd, pây; Khotanese fad; Av. pad- "foot;" cf. Skt. pat; Gk. pos, genitive podos; L. pes, genitive pedis; E. foot, as above; PIE *pod-/*ped-.

barâye (#)

Fr.: pour   

A preposition used to indicate the object or purpose of an action.

M.E., from O.E. for "before, in the sight of, in the presence of" (source also of Old Saxon furi "before," Old Frisian for, Middle Dutch vore, Dutch voor "for, before;" German für "for;" Danish for "for," før "before;" Gothic faur "for," faura "before"), from PIE root *per- "forward," hence "in front of, before," etc.

Barâye "because of," related to Pers. cerâ "for what reason, why?," irâ "for this reason, therefore," zirâ "because, on account of;" also rây "opinion, consult," Mid.Pers. râd, rây "because of, for the sake of, on behalf of;" O.Pers. "reason, cause," in rādiy "for this reason," → reason.

Forbes effect
  اسکر ِ فوربز   
oskar-e Forbes

Fr.: effet Forbes   

Increased reddening and monochromaticity of light as the path length in the air increases.

After the Scottish physicist James David Forbes (1809-1868); → effect.

bažkam (#)

Fr.: interdit   

1) General: Not allowed; prohibited.
2) Physics: Involving a change in → quantum numbers that is not permitted by the → selection rules, → forbidden transition.

Past participle of forbid, from O.E. forbeodan, from for- "against" + beodan "to command" (O.E. biddan"to beg, ask, demand;" cf. Ger. bitten "to ask"); cf. Du. verbieden, O.H.G. farbiotan, Ger. verbieten.

Bažkam in classical Persian dictionaries "a keeping back, a preventing," from Av. paitigam- "to prevent," from paiti- "opposite, against, back, in return" (O.Pers. paity "agaist, back, opposite to, toward, face to face, in front of;" Mod.Pers. variants pâd- (→ anti-); cf. Skt. práti "opposite, against, again, back, in return, toward;" Gk. proti, pros "face to face with, toward, in addition to, near;" PIE *proti) + gam- "to come; to go," jamaiti "goes;" O.Pers. gam- "to come; to go;" Mod./Mid.Pers. gâm "step, pace," âmadan "to come" (cf. Skt. gamati "goes;" Gk. bainein "to go, walk, step;" L. venire "to come;" Tocharian A käm- "to come;" O.H.G. queman "to come;" E. come; PIE root *gwem- "to go, come").

forbidden band
  باند ِ بژکم   
bând-e bažkam

Fr.: bande interdite   

In → solid state physics, a range of → energy levels which is not attained by any electrons in a → crystal. In the energy level diagram forbidden bands appear as gaps between → allowed bands.

forbidden; → band .

forbidden emission line
  خط ِ گسیلی ِ بژکم   
xat-e gosili-ye bažkam

Fr.: raie d'émission interdite   

A → forbidden line in → emission.

forbidden; → emission; → line.

forbidden line
  خط ِ بژکم   
xatt-e bažkam

Fr.: raie interdite   

A spectral line emitted by atoms undergoing energy transitions not normally allowed by the → selection rules of → quantum mechanics. Forbidden emission lines form in low-density interstellar gas and are collisionally excited. They are designated by enclosing in brackets, e.g. [O III] and [N II], O and N representing oxygen and nitrogen atoms respectively.

forbidden; → line.

forbidden transition
  گذرش ِ بژکم   
gozareš-e bažkam

Fr.: transition interdite   

A transition between two quantum mechanical → states that → violates the quantum mechanical → selection rules.

forbidden; → transition.

Forbush decrease
  کاهش ِ فورباش   
kâheš-e Forbush

Fr.: effet Forbush   

A decrease in the Galactic cosmic flux around sunspot maximum as a consequence of Solar flare activity. When sunspots explode, they often hurl massive clouds of hot gas away from the Sun, a phenomenon called → coronal mass ejections (CME). The CMEs contain not only gas but also magnetic fields. So when a CME sweeps past Earth, it also sweeps away many of the electrically-charged cosmic rays.

After Scott E. Forbush, American physicist who studied cosmic rays in the 1930s and 40s; → effect; decrease, from O.Fr. stem of descreistre, from L. decrescere, from → de- "away from" + crescere "to grow."

Kâheš, verbal noun of kâstan, kâhidan "to decrease," from Mid.Pers. kâhitan, kâstan, kâhênitan "to decrease, diminish, lessen;" Av. kasu- "small, little" (Mod.Pers. keh), Proto-Iranian *kas- "to be small, diminish, lessen."

niru (#)

Fr.: force   

1) The cause of a change in motion or shape of a body.
2) A → vector quantity defined by → Newton's second law as the rate of change of → momentum or, equivalently, as the product of → mass and → acceleration. A force is completely specified by giving its magnitude, direction, and point of application. In mechanics, force represents the quantitative measure of the mechanical interaction of material bodies.

From O.Fr. force, from L.L. fortia, from neut. pl. of L. fortis "strong," from forctus, from PIE base *bhergh- "high" (cf. Av. barəz- "high, mount," barezan- "height;" O.Pers. baršan- "height;" Mod.Pers. borz in (the mountain chain) Alborz, and borz "height, magnitude," bâlâ "up, above, high, elevated, height," Lori dialect berg "hill, mountain;" Skt. bhrant- "high;" O.E. burg, burh "castle, fortified place," from P.Gmc. *burgs "fortress;" Ger. Burg "castle," Goth. baurgs "city," E. burg, borough, Fr. bourgeois, bourgeoisie, faubourg).

Niru, from Mid.Pers. nêrok, Av. nairya- "manly, male" (cf. Skt. nárya-), from nar- "man, male" (Mid./Mod.Pers. nar- "male," Skt. nár- "male").

force field
  میدان ِ نیرو   
meydân-e niru (#)

Fr.: champ de force   

Same as → field of force.

force; → field.

force multiplier parameter
  پارامون ِ بستاگر ِ نیرو   
pârâmun-e bastâgar-e niru

Fr.: paramètre de multiplicateur de force   

One of the three quantities (k, α, and δ) which are used in the → radiation-driven wind theory to express the radiation pressure due to spectral lines. These coefficients parametrize the radiation acceleration as: grad≅ k(dv/dr)αge, where ge = σeL/4πcR*2 is the radiative acceleration by electron scattering. The parameter k is dependent on the number of lines that produce the radiation pressure. The parameter α depends on the optical depth of the driving lines and varies between 0 (optically thin) and 1 (optically thick). The parameter δ describes the dependence of k on the density with k ≅ ρδ. The velocity law of radiation-driven winds depends on α and δ, but not on k. The → mass loss rate depends on k, α, and δ (Castor et al. 1975, ApJ 195, 157; Lamers et al., 1995, ApJ 455, 269 and references therein).

force; → multiplier; → parameter.

force system
  راژمان ِ نیروها   
râžmân-e niruhâ

Fr.: système de forces   

Any set of forces acting on a → rigid body.

force; → system.

force-free magnetic field
  میدان ِ مغناتیسی ِ بی‌نیرو   
meydân-meqnâtisi-ye bi-niru

Fr.: champ magnétique sans force   

The condition in a plasma when the → Lorentz force is zero, that is when the electric current flows along the magnetic field. Force-free magnetic fields are encountered in astrophysical plasmas with negligible gas pressure. The solar corona is the best available example of such fields in action in a plasma.

force; → free; → magnetic; → field.

zuri (#)

Fr.: forcé   

1) Physics: Caused by an external force. → forced oscillation.
2) General: Subjected to force, compulsory.

Adjective from → force.

Adjective from zur, → strength.

forced flow
  تچان ِ زوری   
tacân-e zuri

Fr.: écoulement forcé   

A fluid flow generated when external forces cause the fluid to flow, for example when a flow is caused by a pump. It contrasts with → free flow.

forced; → flow.

forced oscillation
  نوش ِ زوری   
naveš-e zuri

Fr.: oscillation forcée   

The oscillation of a system or object induced by an external periodic force. See also → free oscillation.

forced; → oscillation.

araš (#)

Fr.: avant bras   

The part of the arm between the → elbow and the → wrist.

From fore- a prefix meaning "before; front; superior," related to → per-; → arm.

Araš, variant ârenj "elbow;" Mid.Pers. âranj; O.Pers. arašan- "cubit;" Av. arəθnâ- "elbow;" Skt. aratni- "elbow," Iranian stem aratan-, araθn-, borrowed from Iranian into General Slavic as aršin "ell."


Fr.: avant-plan   

The ground or parts situated, or represented as situated, in the front; the portion of a scene or stellar field nearest to the viewer. → background.

From fore, from O.E. fore (prep.) "before, in front of;" (adv.) "before, previously" (cf. O.H.G. fora, Ger. vor, Goth. faiura); from PIE *per-/*pr- (cf. Skt. pura "before, formerly;" Av. paro "before;" Hittite para- "on, forth;" Gk. paros "before," para "from beside, beyond," peri "around, about, toward," pro "before;" L. pro "before, for, instead of," prae "before," per "through, for") + ground, from M.E., from O.E. grund; akin to O.H.G. grunt "ground."

Pišzaminé, from piš- "before; in front," from Mid.Pers. pêš "before, earlier;" O.Pers. paišiya "before; in the presence of" + ziminé "ground," from zamin "earth, ground" → earth.

foreground absorption
  درشم ِ پیش-زمینه   
daršam-e pišzaminé

Fr.: absorption d'avant-plan   

Loss of radiant energy received from an astronomical object due to the presence of absorbing matter situated between the object and observer.

foreground; → absorption.

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