Exoplanet atmospheres

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Simulating gas kinematic studies of high-redshift galaxies with the HARMONI integral field spectrograph

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 498:2 (2020) 1891-1904

Authors:

Mark LA Richardson, Laurence Routledge, Niranjan Thatte, Matthias Tecza, Ryan CW Houghton, Miguel Pereira-Santaella, Dimitra Rigopoulou
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Erratum: The first planet detected in the WTS: an inflated hot-Jupiter in a 3.35 day orbit around a late F-star

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 497:1 (2020) 916-916

Authors:

M Cappetta, RP Saglia, JL Birkby, J Koppenhoefer, DJ Pinfield, ST Hodgkin, P Cruz, G Kovács, B Sipőcz, D Barrado, B Nefs, YV Pavlenko, L Fossati, C del Burgo, EL Martín, I Snellen, J Barnes, D Campbell, S Catalan, MC Gálvez-Ortiz, N Goulding, C Haswell, O Ivanyuk, H Jones, M Kuznetsov, N Lodieu, F Marocco, D Mislis, F Murgas, R Napiwotzki, E Palle, D Pollacco, L Sarro Baro, E Solano, P Steele, H Stoev, R Tata, J Zendejas
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Mineral cloud and hydrocarbon haze particles in the atmosphere of the hot Jupiter JWST target WASP-43b

Astronomy & Astrophysics EDP Sciences 641 (2020) A178-A178

Authors:

Ch Helling, Y Kawashima, V Graham, D Samra, KL Chubb, M Min, LBFM Waters, V Parmentier

Abstract:

Context. Having a short orbital period and being tidally locked makes WASP-43b an ideal candidate for the James Webb Space Telescope (JWST) phase curve measurements. Phase curve observations of an entire orbit will enable the mapping of the atmospheric structure across the planet, with different wavelengths of observation allowing different atmospheric depths to be seen. Aims. We provide insight into the details of the clouds that may form on WASP-43b and their impact on the remaining gas phase, in order to prepare the forthcoming interpretation of the JWST and follow-up data. Methods. We follow a hierarchical modelling strategy. We utilise 3D GCM results as input for a kinetic, non-equilibrium model for mineral cloud particles and for a kinetic model to study a photochemically-driven hydrocarbon haze component. Results. Mineral condensation seeds form throughout the atmosphere of WASP-43b. This is in stark contrast to the ultra-hot Jupiters, such as WASP-18b and HAT-P-7b. The dayside is not cloud free but it is loaded with few yet large mineral cloud particles in addition to hydrocarbon haze particles of a comparable abundance. Photochemically driven hydrocarbon haze appears on the dayside, but it does not contribute to the cloud formation on the nightside. The geometrical cloud extension differs across the globe due to the changing thermodynamic conditions. Day and night differ by 6000 km in pressure scale height. As reported for other planets, the C/O is not constant throughout the atmosphere and varies between 0.74 and 0.3. The mean molecular weight is approximately constant in a H2-dominated WASP-43b atmosphere because of the moderate day/night-temperature differences compared to the super-hot Jupiters. Conclusions. WASP-43b is expected to be fully covered in clouds which are not homogeneously distributed throughout the atmosphere. The dayside and the terminator clouds are a combination of mineral particles of locally varying size and composition as well as of hydrocarbon hazes. The optical depth of hydrocarbon hazes is considerably lower than that of mineral cloud particles such that a wavelength-dependent radius measurement of WASP-43b would be determined by the mineral cloud particles but not by hazes.
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Non-local thermodynamic equilibrium transmission spectrum modelling of HD 209458b

Astronomy & Astrophysics EDP Sciences 641 (2020) A47-A47

Authors:

ME Young, L Fossati, TT Koskinen, M Salz, PE Cubillos, K France

Abstract:

Context. Exoplanetary upper atmospheres are low density environments where radiative processes can compete with collisional ones and introduce non-local thermodynamic equilibrium (NLTE) effects into transmission spectra. Aims. We develop a NLTE radiative transfer framework capable of modelling exoplanetary transmission spectra over a wide range of planetary properties. Methods. We adapted the NLTE spectral synthesis code Cloudy to produce an atmospheric structure and atomic transmission spectrum in both NLTE and local thermodynamic equilibrium (LTE) for the hot Jupiter HD 209458b, given a published T–P profile and assuming solar metallicity. Selected spectral features, including Hα, NaI D, HeI λ10 830, FeI and II ultra-violet (UV) bands, and C, O, and Si UV lines, are compared with literature observations and models where available. The strength of NLTE effects are measured for individual spectral lines to identify which features are most strongly affected. Results. The developed modelling framework that computes NLTE synthetic spectra reproduces literature results for the HeI λ10 830 triplet, the NaI D lines, and the forest of FeI lines in the optical. Individual spectral lines in the NLTE spectrum exhibit up to 40% stronger absorption relative to the LTE spectrum.
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The Equatorial Jet Speed on Tidally Locked Planets. I. Terrestrial Planets

ASTROPHYSICAL JOURNAL 901:1 (2020) ARTN 78

Authors:

Mark Hammond, Shang-Min Tsai, Raymond T Pierrehumbert
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