THE TRUE AND APPARENT ELLIPTICAL ORBITS OF A VISUAL BINARY STAR

Year 2018, Volume: 60 Issue: 2, 51 - 62, 01.08.2018

Esmat Bekir

Abstract

Observation of binary star orbits reveals only the apparent orbit of these two celestial

bodies which differs from the true orbit. Due to the inclination of the plane of the true orbit one

can only observe its projection onto the plane of sky. Computing the true orbit from the apparent

orbit is based on constructing the auxiliary ellipse. This process is well known (Kallrath 2009) but

requires arduous numerical computations. In this paper a simpler approach to obtain the auxiliary

ellipse is presented and its derivation is provided. This approach finds out that the coefficients of

the auxiliary ellipse are very simple functions of those of the apparent ellipse.

Keywords

celestial mechanics, binary stars, auxiliary ellipse, true orbit

References

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