Yazar "Ibanoglu, C" seçeneğine göre listele

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    Öğe
    Orbital period changes of ALGOL-type binaries: S Equulei and AB Cassiopeiae
    (Univ Chicago Press, 2003) Soydugan, F; Demircan, O; Soydugan, E; Ibanoglu, C
    The orbital periods of two Algol-type binaries, S Equ and AB Cas, are studied based on all available times of minima. It is found that the O-C variations of both systems can be represented by a parabolic and a periodic term. S Equ has an accretion region due to mass transfer as shown by Richards and coworkers and Richards & Albright. On the other hand, Zola obtained a light-curve solution with a third light. Our study reveals evidence of mass transfer and third component stars in both systems. The parabolic terms in the O-C variations are due to mass transfer from less massive to more massive components, which is consistent with the semidetached nature of both systems. The periodic terms are explained with the additional third stars in the systems. It is interesting that there is no sign of a magnetic braking effect from the cool secondary in the O-C variation of either system.
  • [ X ]
    Öğe
    The connection between the pulsational and orbital periods for eclipsing binary systems
    (Oxford Univ Press, 2006) Soydugan, E; Ibanoglu, C; Soydugan, F; Akan, MC; Demircan, O
    Considering a sample of 20 eclipsing binary systems with delta Scuti type primaries, we discovered that there is a possible relation among the pulsation periods of the primaries and the orbital periods of the systems. According to this empirical relation, the longer the orbital period of a binary, the longer the pulsation period of its pulsating primary. Among the sample, the masses of the secondaries and the separations between the components are known for eight systems for which a log P-puls versus log F (the gravitational pull exerted per gram of the matter on the surface of the primaries by the secondaries) diagram also verifies such an interrelation between the periods. So, as the gravitational force applied by the secondary component onto the pulsating primary increases, its pulsation period decreases. The detailed physics underlying this empirical relation between the periods needs further confirmation, especially theoretically. However, one must also consider the fact that the present sample does not contain a sufficiently large sample of longer period (P > 5 d) binaries.