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

Actually in operation or in force; concrete; real.

M.E., from L. effectivus "practical," from effect(us), p.p. of efficere, → effect + -ivus "-ive."

Oskarmand, from oskar, → effect + -mand possession suffix.

Of an antenna, the ratio of the extracted power by the antenna to the power per unit area (power density) in the incident wave.

→ effective; → aperture.

The effective value of the → Eddington parameter in a non-homogeneous system (porous opacity).

→ effective; → Eddington limit; → parameter.

The focal length of an imaging system, which consists of several lenses or mirrors.

→ effective; → focal length.

In a → rotating star, the sum of the → gravity and the → centrifugal acceleration. The effective gravity is a function of the rotation velocity (Ω) and the → colatitude (θ). At the pole (θ = 0°) and the equator (θ = 90°) the effective gravity is radial. See also → total gravity.

→ effective; → gravity.

Of a galaxy, the distance from its center within which half of the total luminosity is included.

→ effective; → radius.

A measure of the surface temperature of a star derived from the total emitted energy, assuming that the star is a → blackbody emitter (→ Stefan-Boltzmann law, → Planck's radiation law). See also → brightness temperature; → color temperature.

→ effective; → temperature.

The degree to which goals are achieved and the extent to which posed problems are solved. Compare → efficiency.

→ effective; → -ness.