Remarks on Erratic Period Fluctuations of Detached Close Binaries and the Constancy of the Orbital Period of XY UMa
Abstract
It is shown that the erratic changes of the orbital period, which are observed in some detached eclipsing binary systems, cannot be interpreted as real if their light curves show changing anomalies with asymmetric minimum profiles. In this case the photometrically determined times of the minima do not coincide with the ideal geometric ones, which are unobservable. This fact and the applied reduction methods for deriving the photometric times of minima cause systematic period errors of cumulative character. The discussion of six photoelectricallydetermined minima obtained within the last 20 yr, and earlier photographic ones of the 0^{d}.479 period eclipsing binary XY UMa yields a constant period. The long cyclic light curve variations due to starspot activity of the larger and hotter component of this system are reflected in corresponding period oscillations.
 Publication:

Astrophysics and Space Science
 Pub Date:
 May 1977
 DOI:
 10.1007/BF00643045
 Bibcode:
 1977Ap&SS..48..137G
 Keywords:

 Eclipsing Binary Stars;
 Light Curve;
 Orbit Calculation;
 Celestial Mechanics;
 Orbital Elements;
 Stellar Models;
 Tables (Data);
 Astrophysics