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

The state of a rigid body which is not moving at all. The conditions for static equilibrium are: 1) the sum of the external forces on the object must equal zero, and 2) the sum of the → torques must equal zero. See also → dynamic equilibrium and → mechanical equilibrium.

→ static; → equilibrium.

Same as → stationary limit.

→ static; → limit.

In → fluid mechanics, the → pressure felt by an object suspended in a → fluid and moving with it. This pressure is called static because the object is not moving relative to the fluid. See also → dynamic pressure.

→ static; → pressure.

A closed Universe of finite volume with a constant radius of curvature.

→ static; → Universe.

The branch of → mechanics which studies the laws of composition of forces and the conditions of equilibrium of material bodies under the action of forces.

→ static; → -ics.

Istâyik, from istâ, → static + -ik, → -ics.

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").

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").

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

→ stationary; → black hole.

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.

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

→ stationary; → noise.

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.

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

→ stationary; → phase.

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.

An artificial satellite in a synchronous orbit. → geostationary orbit

→ stationary; → satellite.

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 X_t1 and X_t2 only depends on the interval t₁ and t₂.

→ stationary; → time; → series.

Same as → standing wave.

→ stationary; → wave.

Of, pertaining to, consisting of, or based on → statistics.

Statistic, from → statistics + → -al.

The process of collecting, manipulating, analyzing, and interpreting quantitative data to uncover underlying causes, patterns, and relationships between variables.

→ statistical; → analysis.

A state in which the average density of atoms per cubic centimeter in any atomic state does not change with time and in which, statistically, energy is equally divided among all degrees of freedom if classical concepts prevail.

→ statistical; → equilibrium.

An assumed statement about the way a → random variable is distributed. A statistical hypothesis generally specifies the form of the → probability distribution or the values of the parameters of the distribution. The statement may be true or false. See also → null hypothesis.

→ statistical; → hypothesis.