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Paper: Combining Astrometry and Light-time Effect: Low-mass Companions around Eclipsing Systems
Volume: 335, The Light-Time Effect in Astrophysics: Causes and Cures of the O - C diagram
Page: 55
Authors: Ribas, I.
Abstract: We discuss a method to determine orbital properties and masses of low-mass bodies orbiting eclipsing binaries based on combined analyses of light-travel time (LTT) and astrometry. The presence of a third body causes the relative distance of the eclipsing pair to the Earth to change as it orbits the barycenter of the triple system, thus causing periodic variations of the eclipse arrival times. Studies of the eclipsing systems V471 Tau and R CMa are presented to illustrate the method. The eclipse timings of V471 Tau indicate the presence of a third body with substellar minimum mass. In R CMa the companion is an M-type star or a white dwarf with a minimum mass of about 0.3 MSolar. The same reflex motion responsible for LTT effects also causes a displacement of the binary pair around the barycenter. The combination of the LTT analysis and accurate astrometry leads to the determination of the orbital inclination and thus to a full characterization of the orbital and physical properties of the tertiary component. With the upcoming microarcsecond-level astrometric missions, the technique that we discuss can be successfully applied to detect long-period planetary-size objects and brown dwarfs around eclipsing binaries.
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