An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



<< < acc flo lin lun sub > >>

Number of Results: 94 Search : low
flow tube
  لوله‌ی ِ تچان   
lule-ye tacân

Fr.: tube d'écoulement   

Same as → stream tube.

flow; → tube.


Fr.: aptitude à s'écouler, coulabilité   

The ability of a body of matter (liquid, gas, loose particulate solid) to flow.

From flowable, adj. from → flow + → -able + → -ity.

Tacandegi, from tacandé (originally tacandag), agent noun of tacidan, → flow, + noun suffix -i.

follow-up observation
  نپاهش ِ پیگیر   
nepâheš-e peygir


An observation which expands previous observations and aims at obtaining complementary data in particular with other telescopes/instruments.

Follow-up, from follow, from O.E. folgian, fylgan "to follow, pursue," from W.Gmc. *fulg- (cf. O.Fris. folgia, M.Du. volghen, Ger. folgen "to follow") + up, O.E. up, uppe (cf. Du. op, Ger. auf "up, upward"), from PIE base *upo "up from below;" cf. O.Pers./Av. upā; Skt. úpa; Gk. hypo; L. sub, → hypo-; → observation.

Nepâheš, → observation; peygir, from pey "after; step," related to "foot, step, track," → foot, + gir present stem 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").

follower spot
  لکه‌ی ِ پیرو   
lake-ye peyrow

Fr.: tache de queue   

A → sunspot that follows the → leader spot. Sunspots tend to appear in groups consisting of one leader and several follower spots. The leader and the follower spots having opposite polarities.

Agent noun of follow, from O.E. folgian, fylgan "to follow, pursue," from W.Gmc. *fulg- (cf. O.Fris. folgia, M.Du. volghen, Ger. folgen "to follow").

Laké, → spot; peyrow "follower," from pey "step; after," related to "foot, step, track," → foot, + row "going; which goes," present stem of raftan "to go, walk, proceed," Mid.Pers. raftan, raw-, Proto-Iranian *rab/f- "to go; to attack."

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.

free flow
  تچان ِ آزاد   
tacân-e âzâd

Fr.: écoulement libre   

A fluid flow which develops when density differences within the fluid are the only driving forces. See also → forced flow.

free; → flow.

galactic outflow
  استچان ِ کهکشانی   
ostacân-e kahkešâni

Fr.: flot galactique   

galactic-scale outflow.

galactic; → outflow.

galactic-scale outflow
  استچان با مرپل ِ کهکشانی   
ostacân bâ marpel-e kahkešâni

Fr.: flot à l'échelle galactique   

The enormous amounts of → mass and → energy released from active galaxies into the → intergalactic medium. → Supermassive black holes, believed to exist at the centres of active galaxies (→ active galaxy), → accrete matter and liberate huge quantities of energy. The energy output is often observed as → active galactic nuclei (AGN) outflows in a wide variety of forms, e.g. → collimated  → relativistic jets and/or huge overpressured cocoons in → radio, → blueshifted broad → absorption lines in the → ultraviolet and → optical, → warm absorbers and ultrafast outflows in → X-rays, and → molecular gas in → far infrared. Moreover, the processes of → star formation and → supernova explosions release mass/energy into the surroundings. This → stellar feedback heats up, ionizes and drives gas outward, often generating large-scale outflows/→ winds. Galactic outflows are observed at low redshifts reaching a velocity as large as 1000 km s-1 and at high-z up to z ~ 5, sometimes extending over distances of 60-130 kpc. Galactic-scale outflows may be a primary driver of galaxy evolution through the removal of cool gas from star-forming regions to a galaxy's → halo or beyond.

galactic; → scale; → outflow.

geostrophic flow
  تچان ِ زمین‌چرخشی   
tacân-e zamincarxeši

Fr.: écoulement géostrophique   

Oceanography: A flow resulting from → geostrophic balance. In geostrophic flow water moves along the lines of constant pressure or → isobars. Geostrophic flow is characterized by small → Rossby and → Ekman numbers.

geostrophic; → flow.

  ۱) فروز، فروغ، فروزش؛ ۲) فروزیدن   
1) foruz, foruq, foruzeš; 2) foruzidan

Fr.: 1) rougoiement, incandescence, éclat; 2) rougeoyer, s'embraser, être incandescent, luire rouge   

1a) A light emitted by or as if by a substance heated to luminosity; incandescence. 1b) Brightness of color.
2a) To emit bright light and heat without flame; become incandescent.
2b) To shine like something intensely heated.
2c) To exhibit a strong, bright color; be lustrously red or brilliant (
afterglow, → airglow, → counterglow, → nightglow, → skyglow.

M.E. glowen, from O.E. glowan "to shine as if red-hot," ultimately from PIE *ghlo-.

Foruz-, foruzidan, afruxtan "to light, kindle;" related to foruq "light, brightness" (Mid.Pers. payrog "light, brightness"); rôšan "light; bright, luminous;" ruz "day;" Mid.Pers. rošn light; bright," rôc "day;" O.Pers. raucah-; Av. raocana- "bright, shining, radiant," raocah- "light, luminous; daylight;" cf. Skt. rocaná- "bright, shining, roka- "brightness, light;" Gk. leukos "white, clear;" L. lux "light," also lumen "light, window," luna "Moon;" E. light; Ger. Licht; Fr. lumière; PIE base *leuk- "light, brightness."

hot accretion flow
  تچان ِ فربال ِ داغ   
tacân-e farbâl-e dâq

Fr.: écoulement d'accrétion chaud   

A type of → accretion flow by a → compact object such as a → black hole which has a high → virial temperature, is → optically thick, and occurs at lower mass → accretion rates compared with → cold accretion flows. In a hot accretion flow with a very low mass accretion rate, the electron mean free path is very large, and so the accreting → plasma is nearly collisionless. In this type of accretion flow, thermal conduction transports the energy from the inner to the outer regions. As the gas temperature in the outer regions can be increased above the → virial temperature , the gas in the outer regions can escape from the gravitational potential of the central black hole and form outflows, significantly decreasing the mass accretion rate.

cold; → accretion; → flow.

Hubble flow
  تچان ِ هابل   
tacân-e Hubble

Fr.: flot de Hubble   

Hubble-Lemaitre flow.

Hubble; → flow.

Hubble-Lemaitre flow
  تچان ِ هابل-لومتر   
tacân-e Hubble-Lemaître

Fr.: flot de Hubble-Lemaître   

The general outward motion of → galaxy clusters resulting from the → expansion of the Universe.

Hubble-Lemaitre law; → flow.

incompressible flow
  تچان ِ ناتنجیدنی، ~ ِ تنجش‌ناپذیر   
tacân-e nâtanjidani, ~ tanješnâpazir

Fr.: écoulement incompressible   

A flow whose volume or density does not change under pressure, and therefore its density is a constant. In other words, an ideal flow in which the → divergence of velocity is zero. → compressible flow.

incompressible, from → in "not" + → compressible; → flow.


Fr.: afflux, débit entrant   

1) The act or process of flowing in or into. Something that flows in or into. Opposite of → outflow.
2) Meteo: Flow of water into a stream, lake, reservoir, container, basin, aquifer system, etc.

Inflow, from → in- + → flow.

information flow
  تچان ِ ازدایش   
tacân-e azdâyeš

Fr.: flot d'information   

The flow of data into a system or to the end users.

information; → flow.

isentropic flow
  تچان ِ ایزودرگاشت   
tacân-e izodargâšt

Fr.: écoulement isentrope   

A → reversible flow in which the value of → entropy remains → constant; i.e. no energy is added to the flow, and no energy losses occur due to friction or dissipative effects.

isentropic; → flow.

kilowatt-hour (kWh)
kilowatt-sâ'at (#)

Fr.: kilowatt-heure   

A unit of energy equivalent to one kilowatt (1 kW) of power expended for one hour (1 h) of time. The kilowatt-hour is not a standard unit in any formal system, but it is commonly used to measure the consumption of electrical energy. To convert to → joules, use: 1 kWh = 3.6 × 106 J = 3.6 × 1013ergs.

kilo-; → watt-hour.

laminar flow
  تچان ِ ورقه‌ای   
tacân-e varaqe-yi

Fr.: écoulement laminaire   

A flow in which the particles of fluid are moving orderly, and in which adjacent layers or laminas glide smoothly over another with little mixing between them. A laminar flow may rapidly transform into a → turbulent flow for large → Reynolds numbers.

laminar; → flow.

large Reynolds number flow
  تچان با عدد ِ بزرگ ِ رینولدز   
tacân bâ adad-e bozorg-e Reynolds

Fr.: écoulement à grand nombre de Reynolds   

A turbulent flow in which viscous forces are negligible compared to nonlinear advection terms, which characterize the variation of fluid quantities. The dynamics becomes generally turbulent when the Reynolds number is high enough. However, the critical Reynolds number for that is not universal, and depends in particular on boundary conditions.

large; → Reynolds number; → flow.

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