Third Body and Evolution of a Binary System FZ Orionis

Abstract

The aim of this research work is to study the physical properties of a binary system, FZ Orionis, and it’s evolution by Which the studyof the existenceof a third body is the interesting for physical property, too. Observations were doneusing a 0.5 m Richey-Chertian reflecting telescope connected to CCD Photometry by a standard BVR system at Sirindhorn Observatory, Chiang Mai
and Regional Observatory for Publics, Nakhon Ratchasima. The results have show that the binary system, FZ Orionis is a contact binary according to the Roche’s model with the orbital period change of 4.8416×10^-19 sec/year and an orbital period of 0.39998 day. The calculation on the sinusoidal (O-C)₂ curve shows that the exist a third body in this binary system. The first calculated data set using WD program show that FZ Orionis has a mass ratioof 0.14, an inclinationof 68.24 ±0.359 degree, and the second data set show the existence of the third body . The calculatedresult shown that the light of the third body is very low, by which the valuesof L_3b, L_3v and L_3R are -0.0473, -0.0362 and -0.0427 respectively. So, the light of the third body does not affect to the change of the light curves of FZ Orionis. The result indicates the existence of a very less massive body which may lead to the further study on the possibility of the existence of a planet on this binary system.