摘要：We present radial-velocity (RV) measurements for the K giantνOph (= HIP 88048, HD 163917, HR 6698), which reveal two brown dwarf companions with a period ratio close to 6:1. For our orbital analysis we use 150 precise RV measurements taken at the Lick Observatory between 2000 and 2011, and we combine them with RV data for this star available in the literature. Using a stellar mass ofM= 2.7M⊙forνOph and applying a self-consistent N-body model we estimate the minimum dynamical companion masses to bem1sini≈ 22.2MJupandm2sini≈ 24.7MJup, with orbital periodsP1≈ 530 d andP2≈ 3185 d. We study a large set of potential orbital configurations for this system, employing a bootstrap analysis and a systematicχν2grid-search coupled with our dynamical fitting model, and we examine their long-term stability. We find that the system is indeed locked in a 6:1 mean motion resonance (MMR), with Δωand all six resonance anglesθ1–θ6librating around 0°. We also test a large set of coplanar inclined configurations, and we find that the system will remain in a stable resonance for most of these configurations. TheνOph system is important for probing planetary formation and evolution scenarios. It seems very likely that the two brown dwarf companions ofνOph formed like planets in a circumstellar disk around the star and have been trapped in an MMR by smooth migration capture.
关键词：Key wordsentechniques: radial velocitiesplanets and satellites: detectionplanets and satellites: dynamical evolution and stabilitybrown dwarfsplanetary systems
