پایای ِ بیراهش pâyâ-ye birâheš
*Fr.: constante d'aberration*
The maximum amount of the apparent yearly displacement of a star, resulting from the
→ *aberration of starlight*. The value of the constant of
aberration, κ, at J2000.0 is 20".49552.
κ = (*v*/*c*) csc 1", where *v* is the average speed of
the Earth about the Sun and *c* is the → *speed of light*
in vacuum. The Earth's speed is given by:
*v* = 2π*a* / [*P*(1 - *e*^{2})^{1/2}], where
*a* is the → *semi-major axis* of the Earth's
orbit, *e* is the → *eccentricity* of the Earth's orbit, and
*P* is the → *sidereal period* of the Earth.
Same as → *constant of annual aberration*. See also
→ *constant of diurnal aberration*. → *constant*; → *aberration*. |