다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

We explore how well spectra from the James Webb Space Telescope (JWST) will likely constrain bulk atmospheric properties of transiting exoplanets. We start by modeling the atmospheres of archetypal hot Jupiter, warm Neptune, warm sub-Neptune, and cool super-Earth planets with atmospheres that are clear, cloudy, or of high mean molecular weight (HMMW). Next we simulate the λ = 1–11 μm transmission and emission spectra of these systems for several JWST instrument modes for single-transit or single-eclipse events. We then perform retrievals to determine how well temperatures and molecular mixing ratios (CH4, CO, CO2, H2O, NH3) can be constrained. We find that λ = 1–2.5 μm transmission spectra will often constrain the major molecular constituents of clear solar-composition atmospheres well. Cloudy or HMMW atmospheres will often require full 1–11 μm spectra for good constraints, and emission data may be more useful in cases of sufficiently high Fp and high Fp/F*. Strong temperature inversions in the solar-composition hot-Jupiter atmosphere should be detectable with 1–2.5+ μm emission spectra, and 1–5+ μm emission spectra will constrain the temperature–pressure profiles of warm planets. Transmission spectra over 1–5+ μm will constrain [Fe/H] values to better than 0.5 dex for the clear atmospheres of the hot and warm planets studied. Carbon-to-oxygen ratios can be constrained to better than a factor of 2 in some systems. We expect that these results will provide useful predictions of the scientific value of single-event JWST spectra until its on-orbit performance is known.

https://iopscience.iop.org/article/10.3847/0004-637X/817/1/17/pdf

Characterizing transiting exoplanet atmospheres with jwst

The ExoMol database: Molecular line lists for exoplanet and other hot atmospheres

A new hot line list is calculated for 12 CH4 in its ground electronic state. This line list, called 10to10, contains 9.8 billion transitions and should be complete for temperatures up to 1500 K. It covers the wavelengths longer than 1 µm and includes all transitions to upper states with energies below hc · 18 000 cm −1 and rotational excitation up to J = 39. The line list is computed using the eigenvalues and eigenfunctions of CH4 obtained by variational solution of the Schr¨ odinger equation for the rotation–vibration motion of nuclei employing program TROVE and a new ‘spectroscopic’ potential energy surface (PES) obtained by refining an ab initio PES (CCSD(T)-F12c/aug-cc-pVQZ) through least-squares fitting to the experimentally derived energies with J = 0−4 and a previously reported ab initio dipole moment surface (CCSD(T)F12c/aug-cc-pVTZ). Detailed comparisons with other available sources of methane transitions including HITRAN, experimental compilations and other theoretical line lists show that these sources lack transitions both higher temperatures and near-infrared wavelengths. The 10to10 line list is suitable for modelling atmospheres of cool stars and exoplanets. It is available from the CDS data base as well as at www.exomol.com.

/pdf/exomol-line-lists-iv-the-rotation-vibration-spectrum-of-253x94w39t.pdf

ExoMol line lists IV: The rotation-vibration spectrum of methane up to 1500 K

The HITRAN database is a compilation of molecular spectroscopic parameters. It was established in the early 1970s and is used by various computer codes to predict and simulate the transmission and emission of light in gaseous media (with an emphasis on terrestrial and planetary atmospheres). The HITRAN compilation is composed of five major components: the line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, experimental infrared absorption cross-sections (for molecules where it is not yet feasible for representation in a line-by-line form), collision-induced absorption data, aerosol indices of refraction, and general tables (including partition sums) that apply globally to the data. This paper describes the contents of the 2020 quadrennial edition of HITRAN. The HITRAN2020 edition takes advantage of recent experimental and theoretical data that were meticulously validated, in particular, against laboratory and atmospheric spectra. The new edition replaces the previous HITRAN edition of 2016 (including its updates during the intervening years). All five components of HITRAN have undergone major updates. In particular, the extent of the updates in the HITRAN2020 edition range from updating a few lines of specific molecules to complete replacements of the lists, and also the introduction of additional isotopologues and new (to HITRAN) molecules: SO, CH3F, GeH4, CS2, CH3I and NF3. Many new vibrational bands were added, extending the spectral coverage and completeness of the line lists. Also, the accuracy of the parameters for major atmospheric absorbers has been increased substantially, often featuring sub-percent uncertainties. Broadening parameters associated with the ambient pressure of water vapor were introduced to HITRAN for the first time and are now available for several molecules. The HITRAN2020 edition continues to take advantage of the relational structure and efficient interface available at www.hitran.org and the HITRAN Application Programming Interface (HAPI). The functionality of both tools has been extended for the new edition. 

The HITRAN2020 molecular spectroscopic database

Spectroscopy of exoplanetary atmospheres has become a well established method for the characterisation of extrasolar planets. We here present a novel inverse retrieval code for exoplanetary atmospheres. T-REx (Tau Retrieval for Exoplanets) is a line-by-line radiative transfer fully
Bayesian retrieval framework. T-REx includes the following features: 1) the optimised use of molecular line-lists from the ExoMol project; 2) an unbiased atmospheric composition prior selection, through custom built pattern recognition software; 3) the use of two independent algorithms to fully sample the Bayesian likelihood space: nested sampling as well as a more classical Markov Chain Monte Carlo approach; 4) iterative Bayesian parameter and model selection using the full Bayesian Evidence as well as the Savage-Dickey Ratio for nested models, and 5) the ability to
fully map very large parameter spaces through optimal code parallelisation and scalability to cluster computing. In this publication we outline the T-REx framework and demonstrate, using a theoretical hot-Jupiter transmission spectrum, the parameter retrieval and model selection. We investigate the impact of Signal-to-Noise and spectral resolution on the retrievability of individual
model parameters, both in terms of error bars on the temperature and molecular mixing ratios as well as its effect on the model's global Bayesian evidence.

https://iopscience.iop.org/article/10.1088/0004-637X/802/2/107/pdf

Tau-rex i: a next generation retrieval code for exoplanetary atmospheres

We report the analysis of two new spectroscopic observations of the super-Earth 55 Cancri e, in the near infrared, obtained with the WFC3 camera onboard the HST. 55 Cancri e orbits so close to its parent star, that temperatures much higher than 2000 K are expected on its surface. Given the brightness of 55 Cancri, the observations were obtained in scanning mode, adopting a very long scanning length and a very high scanning speed. We use our specialized pipeline to take into account systematics introduced by these observational parameters when coupled with the geometrical distortions of the instrument. We measure the transit depth per wavelength channel with an average relative uncertainty of 22 ppm per visit and find modulations that depart from a straight line model with a 6$\sigma$ confidence level. These results suggest that 55 Cancri e is surrounded by an atmosphere, which is probably hydrogen-rich. Our fully Bayesian spectral retrieval code, T-REx, has identified HCN to be the most likely molecular candidate able to explain the features at 1.42 and 1.54 $\mu$m. While additional spectroscopic observations in a broader wavelength range in the infrared will be needed to confirm the HCN detection, we discuss here the implications of such result. Our chemical model, developed with combustion specialists, indicates that relatively high mixing ratios of HCN may be caused by a high C/O ratio. This result suggests this super-Earth is a carbon-rich environment even more exotic than previously thought.

/pdf/detection-of-an-atmosphere-around-the-super-earth-55-cancri-1v161nz7sy.pdf

Detection of an atmosphere around the super-earth 55 cancri e

Tau-REx (Tau Retrieval of Exoplanets) is a novel, fully Bayesian atmospheric retrieval code custom built for extrasolar atmospheres. In Waldmann et al. (2015) the transmission spectroscopic case was introduced, here we present the emission spectroscopy spectral retrieval for the Tau-REx framework. Compared to transmission spectroscopy, the emission case is often significantly more degenerate due to the need to retrieve the full atmospheric temperature-pressure (TP) profile. This is particularly true in the case of current measurements of exoplanetary atmospheres, which are either of low signal-to-noise, low spectral resolution or both. Here we present a new way of combining two existing approaches to the modelling of the said TP profile: 1) the parametric profile, where the atmospheric TP structure is analytically approximated by a few model parameters, 2) the Layer-by-Layer approach, where individual atmospheric layers are modelled. Both these approaches have distinct advantages and disadvantages in terms of convergence properties and potential model biases. The Tau-REx hybrid model presented here is a new two-stage TP profile retrieval, which combines the robustness of the analytic solution with the accuracy of the Layer-by-Layer approach. The retrieval process is demonstrated using simulations of the hot-Jupiter WASP-76b and the hot SuperEarth 55 Cnc e, as well as on the secondary eclipse measurements of HD189733b.

Tau-REx II: Retrieval of emission spectra

τ-REx (Tau Retrieval of Exoplanets) is a novel, fully Bayesian atmospheric retrieval code custom built for extrasolar atmospheres. In Waldmann et al., the transmission spectroscopic case was introduced, and here we present the emission spectroscopy spectral retrieval for the τ-REx framework. Compared to transmission spectroscopy, the emission case is often significantly more degenerate due to the need to retrieve the full atmospheric temperature–pressure (TP) profile. This is particularly true in the case of current measurements of exoplanetary atmospheres, which are either of low signal-to-noise, low spectral resolution, or both. We present a new way of combining two existing approaches to the modeling of the said TP profile: (1) the parametric profile, where the atmospheric TP structure is analytically approximated by a few model parameters, (2) the layer-by-layer approach, where individual atmospheric layers are modeled. Both of these approaches have distinct advantages and disadvantages in terms of convergence properties and potential model biases. The τ-REx hybrid model presented here is a new two-stage TP profile retrieval, which combines the robustness of the analytic solution with the accuracy of the layer-by-layer approach. The retrieval process is demonstrated using simulations of the hot-Jupiter WASP-76b and the hot-super-Earth 55 Cnc e as well as the secondary eclipse measurements of HD 189733b.

Emma J. Barton

Papers

The ExoMol database: Molecular line lists for exoplanet and other hot atmospheres

Tau-rex i: a next generation retrieval code for exoplanetary atmospheres

Detection of an atmosphere around the super-earth 55 cancri e

Tau-REx II: Retrieval of emission spectra

REx. II. RETRIEVAL OF EMISSION SPECTRA