Formation and evolution of the two 4/3 resonant giants planets in HD 200964

TADEUS DOS SANTOS, M.; CORREA OTTO, J.; MICHTCHENKO, T.; FERRAZ-MELLO, S.

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2014 vol. 573 p. 1 - 15

0004-6361

Context. It has been suggested that HD 200964 is the first exoplanetary system with two Jovian planets evolving in the 4/3 mean-motion resonance (MMR). Previous scenarios to simulate the formation of two giant planets in the stable 4/3 resonance configuration have failed. Moreover, the orbital parameters available in the literature point out an unstable configuration of the planetary pair. Aims: The purpose of this paper is i) to determine the orbits of the planets from the radial velocity measurements and update the value of the stellar mass (1.57 M&sun;); ii) to analyse the stability of the planetary evolution in the vicinity and inside the 4/3 MMR; and iii) to elaborate a possible scenario for the formation of systems in the 4/3 MMR. Methods: We use a previous model to simulate the formation of the stable planetary pair trapped inside the 4/3 resonance. Our scenario includes an interaction between the type I and type II of migration, planetary growth and stellar evolution from the main sequence to the sub-giant branch. The redetermination of the orbits is done using a biased Monte Carlo procedure, while the planetary dynamics is studied using numerical tools, such as dynamical maps and dynamical power spectra. Results: The results of the formation simulations are able to very closely reproduce the 4/3 resonant dynamics of the best-fit configuration obtained in this paper. Moreover, the confidence interval of the fit matches well with the very narrow stable region of the 4/3 MMR. Conclusions: The formation process of the HD 200964 system is very sensitive to the planetary masses and protoplanetary disk parameters. Only a thin, flat disk allows the embryo-sized planets to reach the 4/3 resonant configuration. The stable evolution of the resonant planets is also sensitive to the mass of the central star, because of overlapping high-order resonances inside the 4/3 resonance. Regardless of the very narrow domain of stable motion, the confidence interval of our fit closely matches the stability area.