摘要：We report precise radial velocity (RV) measurements of WASP-47, a G star that hosts three transiting planets in close proximity (a hot Jupiter, a super-Earth, and a Neptune-sized planet) and a non-transiting planet at 1.4 au. Through a joint analysis of previously published RVs and our own Keck-HIRES RVs, we significantly improve the planet mass and bulk density measurements. For the super-Earth WASP-47e (P = 0.79 days), we measure a mass of M⊕, and a bulk density of g cm−3, consistent with a rocky composition. For the hot Jupiter WASP-47b (P = 4.2 days), we measure a mass of M⊕ (1.12 ± 0.04 MJup) and constrain its eccentricity to at 3σ confidence. For the Neptune-size planet WASP-47d (P = 9.0 days), we measure a mass of M⊕ and a bulk density of g cm−3, suggesting that it has a thick H/He envelope. For the outer non-transiting planet, we measure a minimum mass of M⊕ (1.29 ± 0.06 MJup), an orbital period of days, and an orbital eccentricity of . Our new measurements are consistent with but two to four times more precise than previous mass measurements.
