Homogeneously derived transit timings for 17 exoplanets and reassessed TTV trends for WASP-12 and WASP-4

We homogeneously analyse ∼3.2 × 105 photometric measurements for ∼1100 transit lightcurves belonging to 17 exoplanet hosts. The photometric data cover 16 years 2004–2019 and include amateur and professional observations. Old archival lightcurves were reprocessed using up-to-date exoplanetary parameters and empirically debiased limb-darkening models. We also derive self-consistent transit and radial-velocity fits for 13 targets. We confirm the nonlinear TTV trend in the WASP-12 data at a high significance, and with a consistent magnitude. However, Doppler data reveal hints of a radial acceleration about ( − 7.5 ± 2.2) m/s/yr, indicating the presence of unseen distant companions, and suggesting that roughly 10 per cent of the observed TTV was induced via the light-travel (or Roemer) effect. For WASP-4, a similar TTV trend suspected after the recent TESS observations appears controversial and model-dependent. It is not supported by our homogeneus TTV sample, including 10 ground-based EXPANSION lightcurves obtained in 2018 simultaneously with TESS. Even if the TTV trend itself does exist in WASP-4, its magnitude and tidal nature are uncertain. Doppler data cannot entirely rule out the Roemer effect induced by possible distant companions

The multiplanet system TOI-421: A sarm Neptune and a super puffy mini-Neptune Ttransiting a G9 V Star in a visual binary

We report the discovery of a warm Neptune and a hot sub-Neptune transiting TOI-421 (BD-14 1137, TIC 94986319), a bright (V = 9.9) G9 dwarf star in a visual binary system observed by the Transiting Exoplanet Survey Satellite (TESS) space mission in Sectors 5 and 6. We performed ground-based follow-up observations-comprised of Las Cumbres Observatory Global Telescope transit photometry, NIRC2 adaptive optics imaging, and FIbre-fed Echelle Spectrograph, CORALIE, High Accuracy Radial velocity Planet Searcher, High Resolution echelle Spectrometer, and Planet Finder Spectrograph high-precision Doppler measurements-and confirmed the planetary nature of the 16 day transiting candidate announced by the TESS team. We discovered an additional radial velocity signal with a period of five days induced by the presence of a second planet in the system, which we also found to transit its host star. We found that the inner mini-Neptune, TOI-421 b, has an orbital period of P-b = 5.19672 +/- 0.00049 days, a mass of M-b = 7.17 +/- 0.66 M-circle plus, and a radius of R-b = R-circle plus, whereas the outer warm Neptune, TOI-421 c, has a period of P-c = 16.06819 +/- 0.00035 days, a mass of M-c = 16.42(-1.04)(+1.06)M(circle plus), a radius of R-c = 5.09(-0.15)(+0.16)R(circle plus), and a density of rho(c) = 0.685(-0.072)(+0.080) cm(-3). With its characteristics, the outer planet (rho(c) = 0.685(-0.0072)(+0.080) cm(-3)) is placed in the intriguing class of the super-puffy mini-Neptunes. TOI-421 b and TOI-421 c are found to be well-suited for atmospheric characterization. Our atmospheric simulations predict significant Ly alpha transit absorption, due to strong hydrogen escape in both planets, as well as the presence of detectable CH4 in the atmosphere of TOI-421 c if equilibrium chemistry is assumed.KESPRINT collaboration, an international consortium devoted to the characterization and research of exoplanets discovered with space-based missions NASA's Science Mission directorate NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center National Aeronautics & Space Administration (NASA) European Research Council (ERC) 817540 European Research Council under the European Union's Horizon 2020 research and innovation program 832428 CRT foundation 2018.2323 Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) CONICYT FONDECYT 3180246 Millennium Science Initiative, Chilean Ministry of Economy IC120009 Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) CONICYT FONDECYT 1171208 Irish Research Council for Science, Engineering and Technology GOIPD/2018/659 Swedish National Space Agency DNR 65/19 136/13 Australian Research Council 170100521 NASA through Caltech/JPL grant RSA-1006130 NASA through TESS Guest Investigator Program 80NSSC19K1727 Alfred P. Sloan Foundation National Aeronautics & Space Administration (NASA) 80NSSC18K1585 80NSSC19K0379 National Science Foundation (NSF) AST1717000 Spanish Government RYC-2015-17697 FPI-SO from the Spanish Ministry of Economy and Competitiveness (MINECO) SEV-2015-0548-17-2 BES-2017-082610 National Aeronautics & Space Administration (NASA) NNX17AF27G HeisingSimons foundation PLATO grant GOLF CNES grant CONICYT-PFCHA/Doctorado Nacional, Chile 21140646 German Research Foundation (DFG) PA525/18-1 PA525/19-1 PA525/20-1 HA3279/12-1 RA714/14-1 National Aeronautics & Space Administration (NASA