Three sub-Jupiter-mass planets: WASP-69b & WASP-84b transit active K dwarfs and WASP-70Ab transits the evolved primary of a

We report the discovery of the transiting exoplanets WASP-69b, WASP-70Ab and WASP84b, each of which orbits a bright star (V∼ 10). WASP-69b is a bloated Saturn-mass planet (0.26 MJup, 1.06 RJup) in a 3.868-d period around an active mid-K dwarf. We estimate a stellar age of 1 Gyr from both gyrochronological and age-activity relations, though an alternative gyrochronological relation suggests an age of 3 Gyr. ROSAT detected X-rays at a distance of 60±27 ′′ from WASP-69. If the star is the source then the planet could be undergoing massloss at a rate of ∼10 12 g s −1 . This is 1‐2 orders of magnitude higher than the evaporation rate estimated for HD 209458b and HD 189733b, both of which have exhibited anomalouslylarge Lyman-α absorption during transit. WASP-70Ab is a sub-Jupiter-mass planet (0.59 MJup, 1.16 RJup) in a 3.713-d orbit around the primary of a spatially-resolv ed G4+K3 binary, with a separation of 3. ′′ 3 (>800 AU). We exploit the binary nature of the system to construct a Hertzsprung-Russell diagram, from which we estimate its age to be 9‐10 Gyr. WASP-84b is a sub-Jupiter-mass planet (0.69 MJup, 0.94 RJup) in an 8.523-d orbit around an active earlyK dwarf. Of the transiting planets discovered from the ground to date, WASP-84b has the third-longest period. From a combination of gyrochronological and age-activity relations we estimate the age of WASP-84 to be∼1 Gyr. For both the active stars WASP-69 and WASP-84 we find a modulation of the radial velocities with a period similar to the photometrically-de termined stellar rotation period. We fit the residuals with a low-order harmonic series and subtra ct the best fit from the RVs prior to deriving the system parameters. In each case the solution is essentially unchanged, with much less than a 1-σ change to the planetary mass. We found this method of pre-whitening using a harmonic fit to result in a greater reduction in the res idual RV scatter than the oft-used method of pre-whitening with a fit to the RV residuals and the b isector spans.