We report the discoveries of three transiting exoplanets. WASP-91b is a warm Jupiter (1.34 M Jup , 1.03 R Jup ) in a 2.8-day orbit around a metal-rich K3 star. WASP-105b is a warm Jupiter (1.8 M Jup , 0.96 R Jup ) in a 7.9-day orbit around a metal-rich K2 star. WASP-107b is a warm super-Neptune/sub-Saturn (0.12 M Jup , 0.94 R Jup ) in a 5.7-day orbit around a solar-metallicity K6 star. Considering that giant planets seem to be more common around stars of higher metallicity and stars of higher mass, it is notable that the hosts are all metalrich, late-type stars. With orbital separations that place both WASP-105b and WASP-107b in the weak-tide regime, measurements of the alignment between the planets' orbital axes and their stars' spin axes may help us to understand the inward migration of shortperiod, giant planets. The mass of WASP-107b (2.2 M Nep , 0.40 M Sat ) places it in the transition region between the ice giants and gas giants of the Solar System. Its radius of 0.94 R Jup suggests that it is a low-mass gas giant with a H/He-dominated composition. The planet thus sets a lower limit of 2.2 M Nep on the planetary mass above which large gaseous envelopes can be accreted and retained by proto-planets on their way to becoming gas giants. We may discover whether WASP-107b more closely resembles an ice giant or a gas giant by measuring its atmospheric metallicity via transmission spectroscopy, for which WASP-107b is a very good target.
Determining the architecture of multi-planetary systems is one of the cornerstones of understanding planet formation and evolution. Resonant systems are especially important as the fragility of their orbital configuration ensures that no significant scattering or collisional event has taken place since the earliest formation phase when the parent protoplanetary disc was still present. In this context, TOI-178 has been the subject of particular attention since the first TESS observations hinted at the possible presence of a near 2:3:3 resonant chain. Here we report the results of observations from CHEOPS, ESPRESSO, NGTS, and SPECULOOS with the aim of deciphering the peculiar orbital architecture of the system. We show that TOI-178 harbours at least six planets in the super-Earth to mini-Neptune regimes, with radii ranging from 1.152−0.070+0.073 to 2.87−0.13+0.14 Earth radii and periods of 1.91, 3.24, 6.56, 9.96, 15.23, and 20.71 days. All planets but the innermost one form a 2:4:6:9:12 chain of Laplace resonances, and the planetary densities show important variations from planet to planet, jumping from 1.02−0.23+0.28 to 0.177−0.061+0.055 times the Earth’s density between planets c and d. Using Bayesian interior structure retrieval models, we show that the amount of gas in the planets does not vary in a monotonous way, contrary to what one would expect from simple formation and evolution models and unlike other known systems in a chain of Laplace resonances. The brightness of TOI-178 (H = 8.76 mag, J = 9.37 mag, V = 11.95 mag) allows for a precise characterisation of its orbital architecture as well as of the physical nature of the six presently known transiting planets it harbours. The peculiar orbital configuration and the diversity in average density among the planets in the system will enable the study of interior planetary structures and atmospheric evolution, providing important clues on the formation of super-Earths and mini-Neptunes.
We report the discovery of two additional planetary companions to WASP-41 and WASP-47. WASP-41 c is a planet of minimum mass 3.18 ± 0.20 M Jup and eccentricity 0.29 ± 0.02, and it orbits in 421 ± 2 days. WASP-47 c is a planet of minimum mass 1.24 ± 0.22 M Jup and eccentricity 0.13 ± 0.10, and it orbits in 572 ± 7 days. Unlike most of the planetary systems that include a hot Jupiter, these two systems with a hot Jupiter have a long-period planet located at only ∼1 au from their host star. WASP-41 is a rather young star known to be chromospherically active. To differentiate its magnetic cycle from the radial velocity effect induced by the second planet, we used the emission in the Hα line and find this indicator well suited to detecting the stellar activity pattern and the magnetic cycle. The analysis of the Rossiter-McLaughlin effect induced by WASP-41 b suggests that the planet could be misaligned, though an aligned orbit cannot be excluded. WASP-47 has recently been found to host two additional transiting super Earths. With such an unprecedented architecture, the WASP-47 system will be very important for understanding planetary migration.
We report the detection of the first circumbinary planet (CBP) found by Transiting Exoplanet Survey Satellite (TESS). The target, a known eclipsing binary, was observed in sectors 1 through 12 at 30 minute cadence and in sectors 4 through 12 at 2 minute cadence. It consists of two stars with masses of 1.1 M e and 0.3 M e on a slightly eccentric (0.16), 14.6 day orbit, producing prominent primary eclipses and shallow secondary eclipses. The planet has a radius of ∼6.9 R ⊕ and was observed to make three transits across the primary star of roughly equal depths
We report the discovery of the transiting exoplanets WASP-69b, WASP-70Ab and WASP-84b, each of which orbits a bright star (V ∼ 10). WASP-69b is a bloated Saturn-mass planet (0.26 M Jup , 1.06 R Jup ) in a 3.868-d period around an active, ∼1-Gyr, mid-K dwarf. ROSAT detected X-rays 60±27 ′′ from WASP-69. If the star is the source then the planet could be undergoing mass-loss 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 anomalously-large Lyman-α absorption during transit. WASP-70Ab is a sub-Jupiter-mass planet (0.59 M Jup , 1.16 R Jup ) in a 3.713-d orbit around the primary of a spatially-resolved, 9-10-Gyr, G4+K3 binary, with a separation of 3. ′′ 3 ( 800 AU). WASP-84b is a sub-Jupiter-mass planet (0.69 M Jup , 0.94 R Jup ) in an 8.523-d orbit around an active, ∼1-Gyr, early-K dwarf. Of the transiting planets discovered from the ground to date, WASP-84b has the third-longest period. For the active stars WASP-69 and WASP-84, we pre-whitened the radial velocities using a low-order harmonic series. We found this reduced the residual scatter more than did the oft-used method of pre-whitening with a fit between residual radial velocity and bisector span. The system parameters were essentially unaffected by pre-whitening. -planets and satellites: individual: WASP-69b -planets and satellites: individual: WASP-70Ab -planets and satellites: individual: WASP-84b.⋆ Based on observations made with the WASP-South (South Africa) and SuperWASP-North (La Palma) photometric survey instruments, the RISE camera on the 2-m Liverpool Telescope under program PL12B13, and, all located at La Silla: the 60-cm TRAPPIST photometer, EulerCam and the CORALIE spectrograph, both mounted on the 1.2-m Euler-Swiss telescope, and the HARPS spectrograph on the ESO 3.6-m telescope under program 89.C-0151.† The photometric time-series and radial-velocity data used in this work are available at the CDS via anony-
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