

Paper: 
Analysis of the Motion of the Extrasolar Planet HD 120136 Ab in a Binary System: Calculating Unknown Angular Orbital Elements 
Volume: 
496, Living Together: Planets, Host Stars and Binaries 
Page: 
400 
Authors: 
Plávalová, E.; Solovaya, N. A. 
Abstract: 
We have carried out an analysis of the motion of an extrasolar planet orbiting in a binary system, as a particular case of the threebody problem. The following assumptions have been made: a) the planet orbits around one of the binary components (the parent star); b) the distance between the stellar components is greater than that between the parent star and the orbiting planet (the ratio of the semimajor axes is a small parameter); c) the mass of the planet is smaller than the mass of the star, but is not negligible. We employed the Hamiltonian of the system without shortperiod terms, and we expanded it in terms of Legendre polynomials and truncated the expansion after the secondorder terms. Such form of the Hamiltonian enables us to solve the differential equations of motion of our system and analyze of the motion of the extrasolar planet. We have applied this theory to the system HD 120136, and described the possible regions in which the planet can move. The theory permits us to calculate an unknown angular orbital element for the planet HD 120136 Ab, the ascending node: Ω_{1}=134°±14°. The motion of the planet is expected to be stable over long time scales. 



