oortrsquos-constants | space-encyclopedia

Space Travel

23, May, 2012

Space exploration began with the launch of Sputnik and Astrophysics was born as the application of physics to the phenomena observed by Astronomy, which etymologically means laws of the stars.

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Term	Definition
Oort’s Constants	Two empirical quantities contained in mathematical expressions derived by the Dutch astronomer, Jan Oort, for the radial velocity and proper motion of stars resulting from their orbital motion around the centre of the Galaxy, which is assumed to be circular. The expressions take the form ν = A r sin 2l and μ = 0.211B + A cos 2l where ν is radial velocity, μ proper motion, r distance from the Sun and l the star’s galactic longitude. A and B are Oort’s constants; generally accepted VALUES (are 15 kilometres per second per kiloparsec for A and -10 kilometres per second per kiloparsec for B.

Term

Definition

Oort’s Constants

Two empirical quantities contained in mathematical expressions derived by the Dutch astronomer, Jan Oort, for the radial velocity and proper motion of stars resulting from their orbital motion around the centre of the Galaxy, which is assumed to be circular. The expressions take the form ν = A r sin 2l and μ = 0.211B + A cos 2l where ν is radial velocity, μ proper motion, r distance from the Sun and l the star’s galactic longitude. A and B are Oort’s constants; generally accepted VALUES (are 15 kilometres per second per kiloparsec for A and -10 kilometres per second per kiloparsec for B.