An Accurate, Extensive, and Practical Line List of Methane for the HITEMP Database

Hargreaves, Robert J.; Gordon, Iouli E.; Rey, M.; Nikitin, Andrei; Tyuterev, Vladimir G.; Kochanov, Roman V.; Rothman, Laurence S.

doi:10.3847/1538-4365/ab7a1a

Cited by 153 publications

(109 citation statements)

References 123 publications

(186 reference statements)

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“…The total cross correlation signal is comparable to their work in terms of both strength (S/N = 4.6) and position in velocity space. The latter model, shown on the right panel, utilises the cross sections described in this paper and obtained from the HITEMP database (Hargreaves et al 2020). This model shows no significant correlation at the expected position of the planet (marked by dashed lines), thus we are unable to confirm the detection with this more recent line list.…”

Section: Ch 4 : Hd 102195 Bmentioning

confidence: 86%

“…Our CH 4 cross section is calculated from the new HITEMP line list (Hargreaves et al 2020). This new addition to the HITEMP database utilises ab initio calculations with empirical corrections (Rey et al 2017) as well as the HITRAN2016 database (Gordon et al 2017) to produce a high temperature line list up to 2000 K. Hargreaves et al (2020) found good agreement with experimentally measured opacity at high temperature from Hargreaves et al (2015) and Wong et al (2019). The HITEMP line list uses effective lines allowing for efficient computation of opacities for such a large molecule with many billions of transitions.…”

Section: Chmentioning

confidence: 93%

“…We also note that the CH 4 cross section is most accurately determined at low wavenumbers (Hargreaves et al 2020) and this may also influence the overall detection if it is dominated by the higher frequency bands such as the H band. Based on the limited data presented here and the inaccuracy of the orbital solution, in this context we limit to report these caveats and we conclude that it is still challenging to derive firm prescriptions on the methane cross sections without a dedicated follow-up study.…”

Section: Ch 4 : Hd 102195 Bmentioning

confidence: 96%

“…Left panel: cross correlation with models containing cross sections computed from HITRAN2016 (Gordon et al 2017). Right panel: cross correlation with a model containing the recent HITEMP line list (Hargreaves et al 2020). Cross correlation are given as function of systemic velocity and maximum orbital radial velocity.…”

Section: Ch 4 : Hd 102195 Bmentioning

confidence: 99%

“…We choose these line lists based primarily on precise line positions making them the most suitable for HRS in the infrared. Our H 2 O, HCN and NH 3 line lists come from the ExoMol database (Harris et al 2006;Barber et al 2014;Polyansky et al 2018;Coles et al 2019), the CO and CH 4 line list comes from the HITEMP database (Rothman et al 2010;Li et al 2015;Hargreaves et al 2020) and our CO 2 line list is obtained from the Ames database (Huang et al 2017). We additionally also compute the H 2 O cross section using HITEMP to compare the differences between the POKAZA-TEL line list (Polyansky et al 2018).…”

Section: Introductionmentioning

confidence: 99%

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Molecular cross-sections for high-resolution spectroscopy of super-Earths, warm Neptunes, and hot Jupiters

Gandhi

Brogi

Yurchenko

et al. 2020

Monthly Notices of the Royal Astronomical Society

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High-resolution spectroscopy (HRS) has been used to detect a number of species in the atmospheres of hot Jupiters. Key to such detections is accurately and precisely modelled spectra for cross-correlation against the R ≳ 20 000 observations. There is a need for the latest generation of opacities which form the basis for high signal-to-noise detections using such spectra. In this study we present and make publicly available cross-sections for six molecular species, H2O, CO, HCN, CH4, NH3, and CO2 using the latest line lists most suitable for low- and high-resolution spectroscopy. We focus on the infrared (0.95–5 μm) and between 500 and 1500 K where these species have strong spectral signatures. We generate these cross-sections on a grid of pressures and temperatures typical for the photospheres of super-Earth, warm Neptunes, and hot Jupiters using the latest H2 and He pressure broadening. We highlight the most prominent infrared spectral features by modelling three representative exoplanets, GJ 1214 b, GJ 3470 b, and HD 189733 b, which encompass a wide range in temperature, mass, and radii. In addition, we verify the line lists for H2O, CO, and HCN with previous high-resolution observations of hot Jupiters. However, we are unable to detect CH4 with our new cross-sections from HRS observations of HD 102195 b. These high-accuracy opacities are critical for atmospheric detections with HRS and will be continually updated as new data become available.

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Section: Ch 4 : Hd 102195 Bmentioning

confidence: 86%

Section: Chmentioning

confidence: 93%

Section: Ch 4 : Hd 102195 Bmentioning

confidence: 96%

Section: Ch 4 : Hd 102195 Bmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Molecular cross-sections for high-resolution spectroscopy of super-Earths, warm Neptunes, and hot Jupiters

Gandhi

Brogi

Yurchenko

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Multi-line Boltzmann regression for near-electronvolt temperature and CO sensing via MHz-rate infrared laser absorption spectroscopy

et al. 2022

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A mid-infrared laser absorption technique is developed for sensing of temperature and carbon monoxide (CO) number density from 2000 K to above 9000 K. To resolve multiple rovibrational lines, a distributedfeedback quantum cascade laser (DFB-QCL) is modulated across 80% of its current range using a trapezoidal waveform via a bias-tee circuit. The laser attains a spectral scan depth of 1 cm −1 , at a scan frequency of 1 MHz, which allows for simultaneous measurements of four isolated CO transitions near 2011 cm −1 (4.97 µm) with lower-state energies spanning 3,000 to 42,000 cm −1 . The number density and temperature are calculated using a Boltzmann regression of the four population fractions. This method leverages the information contained in each transition and yields a lower uncertainty than using a single line pair. The sensor is validated in shock tube experiments over a wide range of temperatures and pressures (2300-8100 K, 0.3-3 atm). Measurements behind reflected shock waves are compared to a kinetic model of CO dissociation up to 9310 K and are shown to recover equilibrium conditions. The high temperature range of the sensor is able to resolve rapid species and temperature evolution at near electronvolt conditions making it suitable for investigations of high-speed flows, plasma applications, and high-pressure detonations.

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On the synergy between Ariel and ground-based high-resolution spectroscopy

et al. 2022

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Since the first discovery of an extra-solar planet around a main-sequence star, in 1995, the number of detected exoplanets has increased enormously. Over the past two decades, observational instruments (both onboard and on ground-based facilities) have revealed an astonishing diversity in planetary physical features (i. e. mass and radius), and orbital parameters (e.g. period, semi-major axis, inclination). Exoplanetary atmospheres provide direct clues to understand the origin of these differences through their observable spectral imprints. In the near future, upcoming ground and space-based telescopes will shift the focus of exoplanetary science from an era of “species discovery” to one of “atmospheric characterization”. In this context, the Atmospheric Remote-sensing Infrared Exoplanet Large (Ariel) survey, will play a key role. As it is designed to observe and characterize a large and diverse sample of exoplanets, Ariel will provide constraints on a wide gamut of atmospheric properties allowing us to extract much more information than has been possible so far (e.g. insights into the planetary formation and evolution processes). The low resolution spectra obtained with Ariel will probe layers different from those observed by ground-based high resolution spectroscopy, therefore the synergy between these two techniques offers a unique opportunity to understanding the physics of planetary atmospheres. In this paper, we set the basis for building up a framework to effectively utilise, at near-infrared wavelengths, high-resolution datasets (analyzed via the cross-correlation technique) with spectral retrieval analyses based on Ariel low-resolution spectroscopy. We show preliminary results, using a benchmark object, namely HD 209458 b, addressing the possibility of providing improved constraints on the temperature structure and molecular/atomic abundances.

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An Accurate, Extensive, and Practical Line List of Methane for the HITEMP Database

Cited by 153 publications

References 123 publications

Molecular cross-sections for high-resolution spectroscopy of super-Earths, warm Neptunes, and hot Jupiters

Molecular cross-sections for high-resolution spectroscopy of super-Earths, warm Neptunes, and hot Jupiters

Multi-line Boltzmann regression for near-electronvolt temperature and CO sensing via MHz-rate infrared laser absorption spectroscopy

On the synergy between Ariel and ground-based high-resolution spectroscopy

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