Observing transiting planets with JWST

Mollière, P.; Boekel, R. van; Bouwman, J.; Henning, Th.; Lagage, Pierre-Olivier; Min, M.

doi:10.1051/0004-6361/201629800

Cited by 176 publications

(255 citation statements)

References 165 publications

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“…The vibrational-mode absorption features of these condensate clouds are only detectable in the 5-14µm region (Wakeford et al 2015;Molliere et al 2016). Shorter wavelengths are only sensitive to the Mie/Rayleigh scattering slopes/magnitudes of these condensates.…”

Section: Saturation Of Informationmentioning

confidence: 99%

Information Content Analysis for Selection of Optimal JWST Observing Modes for Transiting Exoplanet Atmospheres

Batalha

Line

2017

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The James Webb Space Telescope (JWST) is nearing its launch date of 2018, and is expected to revolutionize our knowledge of exoplanet atmospheres. In order to specifically identify which observing modes will be most useful for characterizing a diverse range of exoplanetary atmospheres, we use an information content based approach commonly used in the studies of Solar System atmospheres. We develop a system based upon these information content methods to trace the instrumental and atmospheric model phase space in order to identify which observing modes are best suited for particular classes of planets, focusing on transmission spectra. Specifically, the atmospheric parameter space we cover is T=600-1800 K, C/O=0.55-1, [M/H]=1-100×Solar for a R=1.39 R J , M=0.59 M J planet orbiting WASP-62-like star. We also explore the influence of a simplified opaque gray cloud on the information content. We find that obtaining broader wavelength coverage over multiple modes is preferred over higher precision in a single mode given the same amount of observing time. Regardless of the planet temperature and composition, the best modes for constraining terminator temperatures, C/O ratios, and metallicity are NIRISS SOSS+NIRSpec G395. If the target's host star is dim enough such that the NIRSpec prism can be used, then it can be used instead of NIRISS SOSS+NIRSpec G395. Lastly, observations that use more than two modes, should be carefully analyzed because sometimes the addition of a third mode results in no gain of information. In these cases, higher precision in the original two modes is favorable.

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Section: Saturation Of Informationmentioning

confidence: 99%

Information Content Analysis for Selection of Optimal JWST Observing Modes for Transiting Exoplanet Atmospheres

Batalha

Line

2017

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“…The absorption cross sections are averaged in each spectral bin. The equilibrium chemistry model from Mollière et al (2017) has been used to determine the mixing ratios for the same pressure and temperature grid by minimizing the Gibbs free energy. We have neglected non-equilibrium gas chemistry which can also be important in the atmospheres of self-luminous gas giants (e.g., Zahnle & Marley 2014).…”

Section: Opacities and Scattering Matricesmentioning

confidence: 99%

Polarized scattered light from self-luminous exoplanets

Stolker

Min

Stam

et al. 2017

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Context. Direct imaging has paved the way for atmospheric characterization of young and self-luminous gas giants. Scattering in a horizontally-inhomogeneous atmosphere causes the disk-integrated polarization of the thermal radiation to be linearly polarized, possibly detectable with the newest generation of high-contrast imaging instruments. Aims. We aim to investigate the effect of latitudinal and longitudinal cloud variations, circumplanetary disks, atmospheric oblateness, and cloud particle properties on the integrated degree and direction of polarization in the near-infrared. We want to understand how 3D atmospheric asymmetries affect the polarization signal in order to assess the potential of infrared polarimetry for direct imaging observations of planetary-mass companions. Methods. We have developed a three-dimensional Monte Carlo radiative transfer code (ARTES) for scattered light simulations in (exo)planetary atmospheres. The code is applicable to calculations of reflected light and thermal radiation in a spherical grid with a parameterized distribution of gas, clouds, hazes, and circumplanetary material. A gray atmosphere approximation is used for the thermal structure. Results. The disk-integrated degree of polarization of a horizontally-inhomogeneous atmosphere is maximal when the planet is flattened, the optical thickness of the equatorial clouds is large compared to the polar clouds, and the clouds are located at high altitude. For a flattened planet, the integrated polarization can both increase or decrease with respect to a spherical planet which depends on the horizontal distribution and optical thickness of the clouds. The direction of polarization can be either parallel or perpendicular to the projected direction of the rotation axis when clouds are zonally distributed. Rayleigh scattering by submicronsized cloud particles will maximize the polarimetric signal whereas the integrated degree of polarization is significantly reduced with micron-sized cloud particles as a result of forward scattering. The presence of a cold or hot circumplanetary disk may also produce a detectable degree of polarization ( 1%) even with a uniform cloud layer in the atmosphere.

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“…• For petitCODE and Exo-REM the applied sub-Lorenzian lineshape comes from Hartmann et al (2002) for all molecules except for CO 2 for which a profile from is used (see Mollière et al 2017). …”

Section: Opacitiesmentioning

confidence: 99%

“…We perform, in parallel, a Kolmogorov-Smirnov test (KStest) as done in Mollière et al (2017). If the χ 2 or the p KStest is around 1, then the differences between the approaches correspond to the uncertainties of the JWST.…”

Section: Influence Of the Differing Model Assumptions On The Analysismentioning

confidence: 99%

“…In the near future, the James Webb Space Telescope (JWST, see jwst.stsci.edu), thanks to a large collecting area and a suite of state to the art instruments covering a large wavelength range (0.6-28 microns), will be a key machine to study the atmosphere of exoplanets (e.g. Greene et al 2016;Mollière et al 2017). The JWST will not only be used to study transiting/eclipsing exoplanets, but also exoplanets observed by direct imaging, thanks to its high angular resolution.…”

Section: Introductionmentioning

confidence: 99%

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Toward the Analysis of JWST Exoplanet Spectra: Identifying Troublesome Model Parameters

Baudino

Mollière

Venot

et al. 2017

ApJ

119

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Given the forthcoming launch of the James Webb Space Telescope (JWST) which will allow observing exoplanet atmospheres with unprecedented signal-over-noise ratio, spectral coverage and spatial resolution, the uncertainties in the atmosphere modelling used to interpret the data need to be assessed. As the first step, we compare three independent 1D radiative-convective models: ATMO, Exo-REM and petitCODE. We identify differences in physical and chemical processes taken into account thanks to a benchmark protocol we developed. We study the impact of these differences on the analysis of observable spectra. We show the importance of selecting carefully relevant molecular linelists to compute the atmospheric opacity. Indeed, differences between spectra calculated with Hitran and ExoMol exceed the expected uncertainties of future JWST observations. We also show the limitation in the precision of the models due to uncertainties on alkali and molecule lineshape, which induce spectral effects also larger than the expected JWST uncertainties. We compare two chemical models, Exo-REM and Venot Chemical Code, which do not lead to significant differences in the emission or transmission spectra. We discuss the observational consequences of using equilibrium or out-of-equilibrium chemistry and the major impact of phosphine, detectable with the JWST.Each of the models has benefited from the benchmarking activity and has been updated. The protocol developed in this paper and the online results can constitute a test case for other models.

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Observing transiting planets with JWST

Cited by 176 publications

References 165 publications

Information Content Analysis for Selection of Optimal JWST Observing Modes for Transiting Exoplanet Atmospheres

Information Content Analysis for Selection of Optimal JWST Observing Modes for Transiting Exoplanet Atmospheres

Polarized scattered light from self-luminous exoplanets

Toward the Analysis of JWST Exoplanet Spectra: Identifying Troublesome Model Parameters

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