The Light-time Effect in the Eclipsing Binaries with Early-type Components U CrB and RW Tau
- Authors: Khaliullina A.I.1
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Affiliations:
- Sternberg Astronomical Institute
- Issue: Vol 62, No 4 (2018)
- Pages: 264-272
- Section: Article
- URL: https://journals.rcsi.science/1063-7729/article/view/191553
- DOI: https://doi.org/10.1134/S1063772918040030
- ID: 191553
Cite item
Abstract
A detailed study of the orbital-period variations of the Algol-type eclipsing binaries with earlyspectral- type primary components U CrB and RW Tau has been performed. The period variations in both systems can be described as a superposition of secular and cyclic variations of the period. A secular period increase at a rate of 2.58d × 10−7/year is observed for U CrB, which can be explained if there is a uniform flow of matter from the lower-mass to the higher-mass component, with the total angular momentum conserved. RW Tau features a secular period decrease at a rate of −8.6d × 10−7/year; this could be due to a loss of angular momentum by the binary due to magnetic braking. The cyclic orbital-period variations of U CrB and RWTau can be explained by the motion of the eclipsing binary systems along their long-period orbits. In U CrB, this implies that the eclipsing binary moves with a period of 91.3 years around a third body with mass M3 > 1.13M⊙; in RW Tau, the period of the motion around the third body is 66.6 years, and the mass of the third body is M3 > 1.24M⊙. It also cannot be ruled out that the variations are due to the magnetic cycles of the late-type secondaries. The residual period variations could be a superposition of variations due to non-stationary ejection of matter and effects due to magnetic cycles.
About the authors
A. I. Khaliullina
Sternberg Astronomical Institute
Author for correspondence.
Email: hfh@sai.msu.ru
Russian Federation, Universitetskii pr. 13, Moscow, 119991
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