periastron

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Related to periastrons: Apastron

periastron

(pĕr'ēăs`trən): see apsisapsis
(pl. apsides), point in the orbit of a body where the body is neither approaching nor receding from another body about which it revolves. Any elliptical orbit has two apsides.
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periastron

(pe-ree-ass -tron) The closest approach of the two components of a binary star. At greatest separation the components are at apastron.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Periastron

 

the point in the orbit of a star nearest the primary star around which it is revolving. If the influence of other celestial bodies is negligible, motion conforms to Kepler’s laws of planetary motion. Perturbations, caused by the attraction of a third star or by the aspherical nature of the star’s shape, result in variations in the position of the periastron in space.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

periastron

[¦per·ē¦as·trən]
(astronomy)
The coordinates and time when the two stars of a binary star system are nearest to each other in their orbits.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.