An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 3079 Search : on
star formation rate
  نرخ ِ دیسش ِ ستاره   
nerx-e diseš-e setâré

Fr.: taux de formation d'étoiles   

The rate at which a molecular cloud or a galaxy is currently converting gas into stars. It is given by the ratio of the number of stars to the star formation time-scale.

star formation; → rate.

star formation region
  ناحیه‌ی ِ دیسش ِ ستاره   
nâhiye-ye diseš-e setâré

Fr.: région de formation d'étoiles   

A region in the → interstellar medium where processes of → star formation are going on or have occurred in the past.

star; → formation; → region.

star formation time scale
  مرپل ِ زمانی ِ دیسش ِ ستاره   
marpel-e zamâni-ye diseš-e setâre

Fr.: échelle de temps de formation d'étoiles   

The time necessary for a star to form. It depends inversely on the stellar mass.

star formation; → time scale.

star-forming region
  ناحیه‌ی ِ دیسش ِ ستاره   
nâhiye-ye diseš-e setâré

Fr.: région de formation d'étoiles   

A region in which → star formation is going on.

star; → formation; → region.

station
  ایستگاه   
istgâh (#)

Fr.: station   

A stopping place for trains or other land vehicles, for the transfer of freight or passengers. → space station.

M.E., from O.Fr. station, from L. stationem (nominative statio) "a standing, job, position," related to stare "to stand," cognate with Pers. istâdan "to stand," as below.

Istgâh "standing place," from ist present stem of istâdan "to stand" (Mid.Pers. êstâtan; O.Pers./Av. sta- "to stand, stand still; set;" Av. hištaiti; cf. Skt. sthâ- "to stand;" Gk. histemi "put, place, weigh," stasis "a standing still;" L. stare "to stand;" Lith. statau "place;" Goth. standan; PIE base *sta- "to stand") + gâh "place; time" (Mid.Pers. gâh, gâs "time;" O.Pers. gāθu-; Av. gātav-, gātu- "place, throne, spot;" cf. Skt. gâtu- "going, motion; free space for moving; place of abode;" PIE *gwem- "to go, come").

stationary
  ایست‌ور   
istvar (#)

Fr.: stationnaire   

Having a fixed, unchanging position; motionless. geostationary orbit

M.E. from L. stationarius, in classical L., "of a military station," from statio, → station.

Isatvar, from ist present stem of istâdan "to stand" (Mid.Pers. êstâtan; O.Pers./Av. sta- "to stand, stand still; set;" Av. hištaiti; cf. Skt. sthâ- "to stand;" Gk. histemi "put, place, weigh," stasis "a standing still;" L. stare "to stand;" Lith. statau "place;" Goth. standan; PIE base *sta- "to stand") + -var suffix of possession, variant -ur (Mid.Pers. -uwar, -war; from O.Pers. -bara, from bar- "to bear, carry").

stationary black hole
  سیه‌چال ِ ایست‌ور   
siyah-câl-e istvar

Fr.: trou noir stationnaire   

A → black hole with zero → angular momentum, that does not rotate.

stationary; → black hole.

stationary limit surface
  رویه‌ی ِ حدّ ِ ایست‌ور   
ruye-ye hadd-e istvar

Fr.: surface limite stationnaire   

A property of → space-time outside a → rotating black hole, which consists of a surface which geometrically bounds the → ergosphere outward. At the stationary limit a particle would have to move with the local light velocity in order to appear stationary to a distant observer. This is because the space here is being dragged at exactly the speed of light relative to the rest of space. Outside this limit space is still dragged, but at a rate less than the speed of light. Also known as → static limit.

stationary; → limit; → surface.

stationary noise
  نوفه‌ی ِ ایست‌ور   
nufe-ye istvar

Fr.: bruit stationnaire   

Electronics: A random noise whose intensity remains constant with time.

stationary; → noise.

stationary orbit
  مدار ِ ایست‌ور   
madâr-e istvar

Fr.: orbite stationnaire   

An orbit in which the satellite revolves about the primary at the angular rate at which the primary rotates on its axis. From the primary, the satellite thus appears to be stationary over a point on the primary.

stationary; → orbit.

stationary phase
  فاز ِ ایست‌ور   
fâz-e istvar

Fr.: phase stationnaire   

Mechanics: The condition of a body or system at rest.

stationary; → phase.

stationary point
  نقطه‌ی ِ ایست‌ور   
noqte-ye istvar

Fr.: point critique, ~ stationnaire   

1) Math.: For a → function y = f(x), a point at which the → tangent to the graph is horizontal. In other words, a point where the → slope is zero: dy/dx = 0.
2) Of a planet, the position at which the rate of change of its apparent → right ascension is momentarily zero.

stationary; → point.

stationary satellite
  ماهواره‌ی ِ ایست‌ور   
mâhvâre-ye istvar

Fr.: satellite stationnaire   

An artificial satellite in a synchronous orbit. → geostationary orbit

stationary; → satellite.

stationary time series
  سری ِ زمانی ِ ایست‌ور   
seri-ye zamâni-ye istvar

Fr.: série temporelle stationnaire   

A → time series if it obeys the following criteria: 1) Constant → mean over time (t). 2) Constant → variance for all t, and 3) The → autocovariance function between Xt1 and Xt2 only depends on the interval t1 and t2.

stationary; → time; → series.

stationary wave
  موج ِ ایست‌ور   
mowj-e istvar

Fr.: onde stationnaire   

Same as → standing wave.

stationary; → wave.

statistical population
  پرینش ِ آماری   
porineš-e âmâri

Fr.: population statistique   

Any collection of individuals or items from which → samples are drawn. See also → finite population, → infinite population.

statistical; → population.

Stefan-Boltzmann constant
  پایای ِ اشتفان-بولتسمن   
pâyâ-ye Stefan-Boltzmann

Fr.: constante de Stefan-Boltzmann   

The constant of proportionality present in the → Stefan-Boltzmann law. It is equal to σ = 5.670 × 10-8 W m-2 K-4 or 5.670 × 10-5 erg cm-2 s-1 K-4.

Stefan-Boltzmann law; → constant.

stellar aberration
  بیراهش ِ ستاره‌ای   
birâheš-e setâre-yi

Fr.: aberration stellaire   

Same as → aberration of starlight .

stellar; → aberratio.

stellar association
  آهزش ِ ستاره‌ای   
âhazeš-e setâre-yi

Fr.: association stellaire   

1) A large, loose grouping of 10 to 1000 stars that are of similar spectral type and share a common origin. The members move together through space, but have become gravitationally → unbound. Stellar associations are primarily identified by their common movement vectors and ages. → OB association; → T association; → R association.
2) An → unbound stellar agglomeration for which the age of the stars is smaller than the → crossing time (Giels & Portegies Zwart, 2010, MNRAS Letters, astro-ph/1010.1720). See also → star cluster.

The concept of stellar association was first introduced by Viktor A. Ambartsumian (1908-1996), Armenian astrophysicist (1947, Stellar Evolution and Astrophysics, Armenian Acad. of Sci.; German translation, Abhandl. Sowjetischen Astron. Ser. 1. 33, 1951). → stellar; → association.

stellar astronomy
  اخترشناسی ِ ستاره‌ای   
axtaršenâsi-ye setâreyi (#)

Fr.: astronomie stellaire   

The branch of astronomy that deals with the study of stars, their physical properties, formation, and evolution. Same as → stellar astrophysics and → stellar physics.

stellar; → astronomy.

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