An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 93 Search : low
mass flow
  تچان ِ جرم   
tacân-e jerm

Fr.: écoulement de masse   

The mass of a fluid that passes a specified unit area in a unit amount of time.

mass; → flow.

mass outflow
  استچان ِ جرم   
ostacân-e jerm

Fr.: écoulement de masse   

The flowing out of mass through various processes from an object, for example in a star forming region or in a close binary.

mass; → outflow.

meridional flow
  تچان ِ نیمروزانی   
tacân-e nimruzâni

Fr.: courant méridien   

Meteo.: A flow between the poles, or between the equator and the poles. A positive value indicates flow away from the equator; a negative value, flow toward the equator.

meridional; → flow.

molecular outflow
  اُستچان ِ مولکولی   
ostacân-e molekuli

Fr.: flot moléculaire   

An outflow of molecular material, often → bipolar, observed in the regions of → star formation. Molecular outflows are thought to be driven by → bipolar jets from → protostars. They are probably → bow shocks which have had time to cool and be observable in molecular lines. Molecular outflows are poorly → collimated compared to the jets and tend to be slow moving (velocities 10-20 km s-1). Some bipolar outflows may be driven by → stellar winds.

molecular; → outflow.

nightglow
  شب‌فروز، شب‌فروغ   
šabforuz, šabforuq

Fr.: luminescence nocturne   

Same as → airglow.

night; → glow.

one-dimensional flow
  تچان ِ یک-وامونی   
tacân-e yek-vâmuni

Fr.: écoulement uni-dimensionnel   

A hypothetical flow in which all the flow parameters may be expressed as functions of time and one space coordinate only. This single space coordinate is usually the distance measured along the center-line of some conduit in which the fluid is flowing (B. Massey, Mechanics of Fluids, Taylor & Francis, 2006).

one; → dimensional; → flow.

outflow
  ا ُستچان   
ostacân

Fr.: flot, écoulement   

The act of flowing out; a fluid that flows out; any outward movement. Opposite of → inflow.

out + → flow.

overflow
  سرریز   
sarriz (#)

Fr.: débordement   

In computers, the condition arising when the result of an arithmetic operation exceeds the capacity of the number representation.

over-; → flow.

Sarriz, from sar, → head, + riz present stem of rixtan "to flow, to pour" (Mid.Pers. rēxtan and rēcitan "to flow;" Av. raēk- "to leave, set free; to yield, transfer," infinitive *ricyā; Mod.Pers; rig in morderig "heritage" (literally, "left by the dead"); cf. Skt. rinakti "he leaves," riti- "stream; motion, course;" L. rivus "stream, brook;" Old Church Slavic rēka "river;" Rus. reka "river;" Goth. rinnan "run, flow," rinno "brook;" O.E. ridh "stream").

Roche lobe overflow (RLOF)
  سرریز ِ لپ ِ رُش   
sarriz-e lap-e Roche

Fr.: débordement du lobe de Roche   

A process in a → binary system when a star fills its → Roche lobe, often by becoming a → giant or → supergiant during the later stages of → stellar evolution. When the star expands, any material that passes beyond the Roche lobe will flow onto the binary → companion, often by way of an → accretion disk. This occurs through the → inner Lagrangian point where the gravity of the two stars cancels. The RLOF is responsible for a number of phenomena including → cataclysmic variables, → Type Ia supernovae, and many → X-ray binary systems.

Roche lobe; → overflow.

shallow
  نژل   
nažal

Fr.: peu profond   

Of little depth; not deep.

M.E. schalowe, akin to O.E. sceald "shallow."

Nažal, from negation prefix na-, → non-, + žal "deep," variant of jal, jol, jul, → deep.

shallow angle
  زاویه‌ی ِ نژل   
zâviye-ye nažal

Fr.: angle faible   

Low angle, → grazing incidence.

shallow; → angle.

skyglow
  نور ِ شهر، فروغ ِ آسمان   
nur-e šahr, foruq-e âsmân

Fr.: illumination du ciel   

The illumination of the night sky in urban areas caused by wasted light shining upward scattered off dust, humidity, and air. Skyglow is a type of → light pollution that results from light fixtures emitting a portion of their light directly upward into the sky. Light scattered in the atmosphere creates an orange-yellow glow above a city or town. Skyglow interferes with sensitive astronomical instruments designed to capture light from distant stars, nebulae, and galaxies. Skyglow can often be detected hundreds of kilometers away.

sky; → glow.

Nur, → light; foruq, → glow; šahr, → city; âsmân, → sky.

slow
  آهسته   
âhesté (#)

Fr.: lent   

Moving or proceeding with little or less than usual speed or velocity.

O.E. slaw "inactive, sluggish;" cf. O.S. sleu "blunt, dull," M.Du. slee, Du. sleeuw "sour, blunt," O.H.G. sleo "blunt, dull," O.N. sljor, Dan. sløv, Swed. slö "blunt, dull."

Âhesté "slow, quiet, tender, soft," ultimately from Proto-Iranian *ā-hasta-ka-, literally "at rest, motionless, seated." The first and third components are affixes, the main component from *had- "to "sit, be seated;" cf. Av. had- "to sit" (nī...hazdiiāt "would sit down"); Pers. nešastan "to sit;" PIE base *sed- "to sit;" cf. Skt. sad- to sit," sidati "sits;" Gk. hezomai "to sit," hedra "seat, chair;" L. sedere "to sit;" O.Ir. suide "seat, sitting;" Welsh sedd "seat;" Lith. sedmi "to sit;" Rus. sad "garden;" Goth. sitan, Ger. sitzen; E. sit.

slow neutron
  نوترون ِ آهسته   
notron-e âhesté (#)

Fr.: neutron lent   

A neutron whose kinetic energy does not exceed about 10 electron-volts. Also called → thermal neutron.

slow; → neutron.

slow nova
  نو-اختر ِ آهسته   
now-axtar-e âhesté

Fr.: nova lente   

A type of nova whose light curve exhibits a characteristically slow development, having a rise time of several days, maximum of several weeks, and slower decline.

slow; → nova.

Slowly Pulsating B star (SPB)
  ستاره‌ی ِ آهسته تپنده‌ی ِ گونه‌ی ِ B   
setâre-ye âhesté tapande-ye gune-ye B

Fr.: étoile B pulsante à longue période   

A member of a class of → B stars that are situated along the → main sequence with → spectral types ranging from B2 to B9 and masses from 3 to 7 → solar masses. In the → H-R diagram the SPB group lies below → beta Cephei variables, which are more massive. SPBs show light and line-profile variations that are multi-periodic with periods of the order of days. This variability is understood in terms of non-radial → stellar pulsations, and their → oscillation modes are high-order → g modes. Theoretical models attribute the pulsational nature of SPBs to the → kappa mechanism, acting in the metal → opacity bump at 2 x 105 K. Their g-mode pulsations penetrate deep into the stellar interior, making these objects very promising for → asteroseismology. Several oscillation modes are excited simultaneously, resulting in periodicities on time scales of the order of months or even years. The prototype of this group is 53 Per. First introduced as a distinct class by Waelkens (1991, A&A 246, 453).

slow; → pulsating; → B star.

snowplow
  برفروب   
barfrub (#)

Fr.: chasse-neige   

A piece of equipment mounted on the front of a vehicle for clearing away snow from roads, railroad tracks, etc.

snow + plow, → Plough.

Barfrub, from barf, → snow, + rub, rubidan "to sweep," → scan.

snowplow phase
  فاز ِ برفروب   
fâz-e barfrub

Fr.: phase de chasse-neige   

The third phase in the evolution of a → supernova remnant (SNR) occurring after the → Sedov-Taylor phase when the mass of the swept-up material becomes much larger than the amount of the ejected material. The SNR is surrounded by a cool → shell of accumulated material that is being pushed from behind, similar to what occurs for a snowplow. During this phase, → radiative cooling becomes important and the total energy is no longer conserved. Also called the → radiative phase.

snowplow; → phase.

steady flow
  تچان ِ پایا   
tacân-e pâyâ

Fr.: écoulement constant, ~ stationnaire   

A flow in which the characterizing conditions, such as → streamlines or velocity at any given point, do not change with time.

steady; → flow.

Tacân, → flow; pâyâ "steady, constant," from pâyidan "to stand firm, to be constant, steady," from Mid.Pers. pattây-, pattutan "to last, endure, stay."

subsonic flow
  تچان ِ زیر-صدایی   
tacân-e zir-sedâyi

Fr.: écoulement subsonique   

A flow in which the velocity of the constituting particles never exceeds that of sound in the same fluid. Also called subcritical flow.

subsonic; → flow.

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