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: 11 Search : stationary
geostationary orbit
  مدار ِ زمین‌ایست‌وّر   
madâr-e zamin-istvar

Fr.: orbite géostationnaire   

A satellite orbit in the plane of the Earth's equator and 35,880 km above it, at which distance the satellite's period of rotation matches the Earth's and the satellite always remains fixed in the same spot over the Earth.

Geostationary, from → geo- + → stationary; → orbit.

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.