HITRAN2016: Part I. Line lists for H2O, CO2, O3, N2O, CO, CH4, and O2

Gordon, Iouli E.; Hill, Christian; Kochanov, Roman V.; Tan, Yan; Rothman, Laurence S.

doi:10.15278/isms.2017.tj08

Cited by 16 publications

(15 citation statements)

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“…The wavelength range that has been probed since the discovery of the system goes from 0.6 µm to 5 µm. In this spectral range the strongest molecular features that we could expect in the absence of clouds and haze -and in a plausible planetary environment -are CO 2 , CH 4 , H 2 O and CO (Tennyson & Yurchenko 2012;Gordon et al 2017;Morley et al 2017). Considering the distribution of the effective wavelength of the different instruments we can only look for some localized, strong features: the CO 2 4.3 µm spectral feature in the 4-5 µm channel of Spitzer/IRAC (width of the bandpass is 1.015 µm for that channel), the CO 2 2.1 µm spectral feature in the VLT/HAWK-I's NB-2090 filter bandpass (width of the bandpass is 0.020 µm for NB-2090 filter), and the CH 4 3.3 µm spectral feature in the 3.15-3.9 µm channel of Spitzer/IRAC (width of the bandpass is 0.750 µm for that channel).…”

Section: Transmission Spectra Of the Planetsmentioning

confidence: 89%

TRAPPIST-1: Global results of theSpitzerExploration Science Program Red Worlds

Ducrot

Gillon

Delrez

et al. 2020

A&A

112

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Context. With more than 1000 h of observation from Feb. 2016 to Oct. 2019, the Spitzer Exploration Program Red Worlds (ID: 13067, 13175 and 14223) exclusively targeted TRAPPIST-1, a nearby (12 pc) ultracool dwarf star, finding that it is orbited by seven transiting Earth-sized planets. At least three of these planets orbit within the classical habitable zone of the star, and all of them are well-suited for a detailed atmospheric characterization with the upcoming JWST. Aims. The main goals of the Spitzer Red Worlds program were (1) to explore the system for new transiting planets, (2) to intensively monitor the planets’ transits to yield the strongest possible constraints on their masses, sizes, compositions, and dynamics, and (3) to assess the infrared variability of the host star. In this paper, we present the global results of the project. Methods. We analyzed 88 new transits and combined them with 100 previously analyzed transits, for a total of 188 transits observed at 3.6 or 4.5 μm. For a comprehensive study, we analyzed all light curves both individually and globally. We also analyzed 29 occultations (secondary eclipses) of planet b and eight occultations of planet c observed at 4.5 μm to constrain the brightness temperatures of their daysides. Results. We identify several orphan transit-like structures in our Spitzer photometry, but all of them are of low significance. We do not confirm any new transiting planets. We do not detect any significant variation of the transit depths of the planets throughout the different campaigns. Comparing our individual and global analyses of the transits, we estimate for TRAPPIST-1 transit depth measurements mean noise floors of ~35 and 25 ppm in channels 1 and 2 of Spitzer/IRAC, respectively. We estimate that most of this noise floor is of instrumental origins and due to the large inter-pixel inhomogeneity of IRAC InSb arrays, and that the much better interpixel homogeneity of JWST instruments should result in noise floors as low as 10 ppm, which is low enough to enable the atmospheric characterization of the planets by transit transmission spectroscopy. Our analysis reveals a few outlier transits, but we cannot conclude whether or not they correspond to spot or faculae crossing events. We construct updated broadband transmission spectra for all seven planets which show consistent transit depths between the two Spitzer channels. Although we are limited by instrumental precision, the combined transmission spectrum of planet b to g tells us that their atmospheres seem unlikely to be CH4-dominated. We identify and model five distinct high energy flares in the whole dataset, and discuss our results in the context of habitability. Finally, we fail to detect occultation signals of planets b and c at 4.5 μm, and can only set 3-σ upper limits on their dayside brightness temperatures (611 K for b 586 K for c).

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Section: Transmission Spectra Of the Planetsmentioning

confidence: 89%

TRAPPIST-1: Global results of theSpitzerExploration Science Program Red Worlds

Ducrot

Gillon

Delrez

et al. 2020

A&A

112

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“…REDFOX includes absorption of 20 molecules 1 using spectroscopic cross sections from the HITRAN 2016 line list (Gordon et al 2017) and 81 molecules using UV and VIS cross sections mainly taken from the MPI Mainz Spectral Atlas (Keller-Rudek et al 2013) as described in Scheucher et al (2020) and Wunderlich et al (2020). Additionally Rayleigh scattering of eight molecules 2 , Mlawer-Tobin-Clough-Kneizys-Davies absorption (MT_CKD; Mlawer et al 2012) Scheucher et al 2020, for details).…”

Section: Model Description and Updatesmentioning

confidence: 99%

“…The simulated atmospheres serve as input to compute transmission spectra with the "Generic Atmospheric Radiation Lineby-line Infrared Code" (GARLIC; Schreier et al 2014Schreier et al , 2018. Line parameters and CIAs are taken from the HITRAN database (Gordon et al 2017;Karman et al 2019). We consider the CKD continuum model for H 2 O (Clough et al 1989) (Murphy 1977;Sneep & Ubachs 2005;Marcq et al 2011).…”

Section: Transmissionmentioning

confidence: 99%

Detectability of biosignatures on LHS 1140 b

Wunderlich

Scheucher

Grenfell

et al. 2021

A&A

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Context. Terrestrial extrasolar planets around low-mass stars are prime targets when searching for atmospheric biosignatures with current and near-future telescopes. The habitable-zone super-Earth LHS 1140 b could hold a hydrogen-dominated atmosphere, and is an excellent candidate for detecting atmospheric features. Aims. In this study we investigate how the instellation and planetary parameters influence the atmospheric climate, chemistry, and spectral appearance of LHS 1140 b. We study the detectability of selected molecules, in particular potential biosignatures, with the upcoming James Webb Space Telescope (JWST) and Extremely Large Telescope (ELT). Methods. In the first step we used the coupled climate–chemistry model 1D-TERRA to simulate a range of assumed atmospheric chemical compositions dominated by molecular hydrogen (H2) and carbon dioxide (CO2). In addition, we varied the concentrations of methane (CH4) by several orders of magnitude. In the second step we calculated transmission spectra of the simulated atmospheres and compared them to recent transit observations. Finally, we determined the observation time required to detect spectral bands with low-resolution spectroscopy using JWST, and the cross-correlation technique using ELT. Results. In H2-dominated and CH4-rich atmospheres oxygen (O2) has strong chemical sinks, leading to low concentrations of O2 and ozone (O3). The potential biosignatures ammonia (NH3), phosphine (PH3), chloromethane (CH3Cl), and nitrous oxide (N2O) are less sensitive to the concentration of H2, CO2, and CH4 in the atmosphere. In the simulated H2-dominated atmosphere the detection of these gases might be feasible within 20 to 100 observation hours with ELT or JWST when assuming weak extinction by hazes. Conclusions. If further observations of LHS 1140 b suggest a thin, clear, hydrogen-dominated atmosphere, the planet would be one of the best known targets to detect biosignature gases in the atmosphere of a habitable-zone rocky exoplanet with upcoming telescopes.

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“…The grey shaded areas show the regions severely affected by telluric absorption. Smette et al 2015), which makes use of the line-by-line radiative transfer model (LBLRTM, Clough et al 2005) and the HITRAN molecular line database (Gordon et al 2017), to model the Earth's atmospheric transmission spectrum. This allowed us to prevent wrong line identification throughout the visual inspection of the reference spectra.…”

Section: Fe I and Fe Ii Line Selectionsmentioning

confidence: 99%

Stellar atmospheric parameters of FGK-type stars from high-resolution optical and near-infrared CARMENES spectra

Marfil

Tabernero

Montes

et al. 2020

Monthly Notices of the Royal Astronomical Society

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With the purpose of assessing classic spectroscopic methods on high-resolution and high signal-to-noise ratio spectra in the near-infrared wavelength region, we selected a sample of 65 F-, G-, and K-type stars observed with CARMENES, the new, ultrastable, double-channel spectrograph at the 3.5 m Calar Alto telescope. We computed their stellar atmospheric parameters (T eff , log g, ξ, and [Fe/H]) by means of the StePar code, a Python implementation of the equivalent width method that employs the 2017 version of the MOOG code and a grid of MARCS model atmospheres. We compiled four Fe i and Fe ii line lists suited to metal-rich dwarfs, metal-poor dwarfs, metal-rich giants, and metal-poor giants that cover the wavelength range from 5 300 to 17 100Å, thus substantially increasing the number of identified Fe i and Fe ii lines up to 653 and 23, respectively. We examined the impact of the near-infrared Fe i and Fe ii lines upon our parameter determinations after an exhaustive literature search, placing special emphasis on the 14 Gaia benchmark stars contained in our sample. Even though our parameter determinations remain in good agreement with the literature values, the increase in the number of Fe i and Fe ii lines when the near-infrared region is taken into account reveals a deeper T eff scale that might stem from a higher sensitivity of the near-infrared lines to T eff .

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HITRAN2016: Part I. Line lists for H2O, CO2, O3, N2O, CO, CH4, and O2

Cited by 16 publications

References 0 publications

TRAPPIST-1: Global results of theSpitzerExploration Science Program Red Worlds

TRAPPIST-1: Global results of theSpitzerExploration Science Program Red Worlds

Detectability of biosignatures on LHS 1140 b

Stellar atmospheric parameters of FGK-type stars from high-resolution optical and near-infrared CARMENES spectra

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