Indications for very high metallicity and absence of methane in the eccentric exo-Saturn WASP-117b

Carone, L.; Mollière, P.; Zhou, Yifan; Bouwman, J.; Yan, F.; Baeyens, Robin; Apai, Dániel; Espinoza, N.; Rackham, Benjamin V.; Jordán, Andrés; Angerhausen, Daniel; Decin, L.; Lendl, M.; Venot, Olivia; Henning, Thomas

doi:10.1051/0004-6361/202038620

Cited by 28 publications

(28 citation statements)

References 108 publications

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“…This could indicate a composition that is far removed from solar values, and/or a combination of a high internal temperature with deep vertical mixing (Kreidberg et al 2018;Fortney et al 2020). Our calculation of yields 10 8 -10 9 cm 2 /s for this WASP-107 b-like model, which should be high enough to quench methane at low abundances, as demonstrated for the comparable planet WASP-117 b (Carone et al 2021). However, a low intrinsic temperature of 200 K has been adopted for all models in this work.…”

Section: Wasp-107 Bsupporting

confidence: 60%

“…For this reason, several attempts have been made to constrain the methane abundance in exoplanet atmospheres, using Hubble Space Telescope WFC3 transmission spectroscopy. However, many of these studies have resulted in an absence of methane absorption, even in the atmospheres of cool planets with equilibrium temperatures below 1000 K (Kreidberg et al 2018;Benneke et al 2019;Carone et al 2021). In one instance, transmission spectroscopy has provided significant evidence for both water and methane absorption (Chachan et al 2019).…”

Section: Observing Methanementioning

confidence: 99%

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Grid of pseudo-2D chemistry models for tidally locked exoplanets – I. The role of vertical and horizontal mixing

Baeyens

Decin

Carone

et al. 2021

Monthly Notices of the Royal Astronomical Society

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The atmospheres of synchronously rotating exoplanets are intrinsically three-dimensional, and fast vertical and horizontal winds are expected to mix the atmosphere, driving the chemical composition out of equilibrium. Due to the longer computation times associated with multi-dimensional forward models, horizontal mixing has only been investigated for a few case studies. In this paper, we aim to generalize the impact of horizontal and vertical mixing on the chemistry of exoplanet atmospheres over a large parameter space. We do this by applying a sequence of post-processed forward models for a large grid of synchronously rotating gaseous exoplanets, where we vary the effective temperature (between 400 K and 2600 K), surface gravity, and rotation rate. We find that there is a dichotomy in the horizontal homogeneity of the chemical abundances. Planets with effective temperatures below 1400 K tend to have horizontally homogeneous, vertically quenched chemical compositions, while planets hotter than 1400 K exhibit large compositional day-night differences for molecules such as CH4. Furthermore, we find that the planet’s rotation rate impacts the planetary climate, and thus also the molecular abundances and transmission spectrum. By employing a hierarchical modelling approach, we assess the relative importance of disequilibrium chemistry on the exoplanet transmission spectrum, and conclude that the temperature has the most profound impact. Temperature differences are also the main cause of limb asymmetries, which we estimate could be observable with the James Webb Space Telescope. This work highlights the value of applying a consistent modelling setup to a broad parameter space in exploratory theoretical research.

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Section: Wasp-107 Bsupporting

confidence: 60%

Section: Observing Methanementioning

confidence: 99%

Grid of pseudo-2D chemistry models for tidally locked exoplanets – I. The role of vertical and horizontal mixing

Baeyens

Decin

Carone

et al. 2021

Monthly Notices of the Royal Astronomical Society

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“…We immediately notice a vertical offset in the spectra obtained by Iraclis and CASCADe. The offset is likely to be caused by differences in the correction of the systematics, and such offsets between different pipelines have been seen before, for example, for WASP-117 b (Anisman et al 2020;Carone et al 2021) 6, and the spectrum recovered in this work. Also plotted are forward models that assume a clear H/He atmosphere with various molecules, each at an abundance of volume mixing ratios of 10 −3 .…”

Section: Comparison With Previous Workmentioning

confidence: 53%

“…CASCADe implements a novel data-driven method, pioneered by Schölkopf et al (2016), utilizing the causal connections within a data set to calibrate the spectral time-series data. For a full description of the pipeline steps, we refer the reader to Carone et al (2021).…”

Section: Comparison With Previous Workmentioning

confidence: 99%

ARES.* V. No Evidence For Molecular Absorption in the HST WFC3 Spectrum of GJ 1132 b

Mugnai

Modirrousta-Galian

Edwards

et al. 2021

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We present a study on the spatially scanned spectroscopic observations of the transit of GJ 1132 b, a warm (∼500 K) super-Earth (1.13 R ⊕ ) that was obtained with the G141 grism (1.125-1.650 μm) of the Wide Field Camera 3 (WFC3) on board the Hubble Space Telescope. We used the publicly available Iraclis pipeline to extract the planetary transmission spectra from the five visits and produced a precise transmission spectrum. We analyzed the spectrum using the TauREx3 atmospheric retrieval code, with which we show that the measurements do not contain molecular signatures in the investigated wavelength range and are best fit with a flat-line model. Our results suggest that the planet does not have a clear primordial, hydrogen-dominated atmosphere. Instead, GJ 1132 b could have a cloudy hydrogen-dominated atmosphere, have a very enriched secondary atmosphere, be airless, or have a tenuous atmosphere that has not been detected. Due to the narrow wavelength coverage of WFC3, these scenarios cannot be distinguished yet, but the James Webb Space Telescope may be capable of detecting atmospheric features, although several observations may be required to provide useful constraints.Unified Astronomy Thesaurus concepts: Exoplanet atmospheres (487); Astronomy data analysis (1858); Hubble Space Telescope (761); Exoplanets (498)

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“…On the other hand, high opacities at lower atmospheric pressures can imprint their spectral signatures on high-resolution spectra, resulting in unambiguous detection of atmospheric atomic and molecular features (e.g., Hoeijmakers et al 2019;Yan et al 2019;Sánchez-López et al 2019;Nortmann et al 2018;Khalafinejad et al 2017). Therefore, a combined or even parallel analysis of both low-and high-resolution spectra provides the complementary information (e.g., Brogi et al 2017;Pino et al 2018;Carone et al 2021) required to fully unveil exoplanet atmospheres.…”

Section: Introductionmentioning

confidence: 99%

Probing the atmosphere of WASP-69 b with low- and high-resolution transmission spectroscopy

Khalafinejad,

Molaverdikhani,

Blecic

et al. 2021

Preprint

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Consideration of both low-and high-resolution transmission spectroscopy is key for obtaining a comprehensive picture of exoplanet atmospheres. In studies of transmission spectra, the continuum information is well established with low-resolution spectra, while the shapes of individual lines are best constrained with high-resolution observations. In this work, we aim to merge high-with lowresolution transmission spectroscopy to place tighter constraints on physical parameters of the atmospheres. We present the analysis of three primary transits of WASP-69 b in the visible (VIS) channel of the CARMENES instrument and perform a combined lowand high-resolution analysis using additional data from HARPS-N, OSIRIS/GTC, and WFC3/HST already available in the literature. We investigate the Na i D 1 and D 2 doublet, Hα, the Ca ii infra-red triplet (IRT), and K i λ7699 Å lines, and we monitor the stellar photometric variability by performing long-term photometric observations with the STELLA telescope. During the first CARMENES observing night, we detected the planet Na i D 2 and D 1 lines at ∼ 7σ and ∼ 3σ significance levels, respectively. We measured a D 2 /D 1 intensity ratio of 2.5±0.7, which is in agreement with previous HARPS-N observations. Our modelling of WFC3 and OSIRIS data suggests strong Rayleigh scattering, solar to super-solar water abundance, and a highly muted Na feature in the atmosphere of this planet, in agreement with previous investigations of this target. We use the continuum information retrieved from the low-resolution spectroscopy as a prior to break the degeneracy between the Na abundance, reference pressure, and thermosphere temperature for the high-resolution spectroscopic analysis. We fit the Na i D 1 and D 2 lines individually and find that the posterior distributions of the model parameters agree with each other within 1σ. Our results suggest that local thermodynamic equilibrium processes can explain the observed D 2 /D 1 ratio because the presence of haze opacity mutes the absorption features.

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Indications for very high metallicity and absence of methane in the eccentric exo-Saturn WASP-117b

Cited by 28 publications

References 108 publications

Grid of pseudo-2D chemistry models for tidally locked exoplanets – I. The role of vertical and horizontal mixing

Grid of pseudo-2D chemistry models for tidally locked exoplanets – I. The role of vertical and horizontal mixing

ARES.* V. No Evidence For Molecular Absorption in the HST WFC3 Spectrum of GJ 1132 b

Probing the atmosphere of WASP-69 b with low- and high-resolution transmission spectroscopy

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