Helen Rovithis-Livaniou

Starspots and photometric noise on observed minus calculated (O{C) diagrams

The eects of starspots on the O{C diagrams of eclipsing binaries are investigated, with a special em- phasis on contact binaries. It is shown that starspots modulate the O{C dierences in a fundamentally dierent way than real orbital period variations. Migrating starspots can only introduce high frequency, low amplitude disturbances (generally less than 0:01 d), whose characteristics are numerically specied for typical contact bina- ries. It becomes evident that the observed systematic short timescale variations of the O{C diagrams of active contact binaries (even those like VW Cep) cannot be attributed to starspots. Furthermore, the basic property of non-linear modulation of O{C dierences is emphasised. This non-linearity has serious consequences for the widespread traditional method of O{C diagram analysis. This traditional method is found inappropriate even on a fundamental level, and its mathematical and physical inconsistencies are reviewed.

Fourier analysis of the light curves of eclipsing variable stars

AbstractThe aim of the present paper is to find the eclipse perturbations, in the frequency-domain, of close eclipsing systems exhibiting partial eclipses.After a brief introduction, in Section 2 we shall deal with the evaluation of thean(l) integrals for partial eclipses and give them in terms ofa00,a00 (of the associated α-functions) and

A photometric study of the W UMa-type system U Pegasi

\mathfrak{J}_{ \pm 1,n}^0

THE ECLIPSING BINARY AB ANDROMEDAE

integrals; while Section 3 gives the eclipse perturbations

A photometric study of V566 ophiuchi

\mathfrak{B}_h^{(l)}

Photoelectric observations of the eclipsing binary U Pegasi

arising from the tidal and rotational distortion of the two components. The