Near 2:1 Mean Motion Resonance Capture and Orbital Evolution of a Hot-Neptune System: HD 106315

Abstract

In this work, we investigate the near 2:1 mean motion resonance (MMR) capture scenario and tidal evolution for the hot-Neptune system HD 106315 by theoretical analysis and numerical simulations. To make a deeper understanding of migration for this system, we extensively explore the initial semi-major axis (SMA), eccentricity, as well as the attenuation coefficient of the eccentricity of HD 106315c that affect the orbital configuration of the system. The numerical simulations show that when the initial orbital elements of two planets are ab∼0.4 au, ac∼0.8 au, eb and ec lower than 0.03, HD 106315b and HD 106315c can migrate to currently observed location, and form near 2:1 mean motion resonance in about 65000 years. This scenario takes into account the gravitational effect of the central star and the viscosity of disk.In addition, the tidal dissipation that originates from the host star, can influence the MMR configuration for planets. From the point of theoretical analysis, the results show that for the tidal dissipation factor Q=100, the ratio of orbital period of two planets will change over the evolution. This may be indicative of the resonant departure for two planets in the system. However, according to numerical simulations, the tidal dissipation factor Q may be larger than 103 for the two planets, therefore we may safely conclude that tidal effect cannot play a major role in driving two Neptunian planets of the HD 106315 system move out of 2:1 mean motion resonance within the residual lifetime of the star.