petitRADTRANS: a Python radiative transfer package for exoplanet characterization and retrieval

Abstract

We present the easy-to-use, publicly available, Python package petitRADTRANS, built for the spectral characterization of exoplanet atmospheres. The code is fast, accurate, and versatile; it can calculate both transmission and emission spectra within a few seconds at low resolution ($\lambda /\Delta \lambda$ = 1000; correlated-k method) and high resolution ($\lambda /\Delta \lambda =10^6$; line-by-line method), using only a few lines of input instruction. The somewhat slower correlated-k method is used at low resolution because it is more accurate than methods such as opacity sampling. Clouds can be included and treated using wavelength-dependent power law opacities, or by using optical constants of real condensates, specifying either the cloud particle size, or the atmospheric mixing and particle settling strength. Opacities of amorphous or crystalline, spherical or irregularly-shaped cloud particles are available. The line opacity database spans temperatures between 80 and 3000 K, allowing to model fluxes of objects such as terrestrial planets, super-Earths, Neptunes, or hot Jupiters, if their atmospheres are hydrogen-dominated. Higher temperature points and species will be added in the future, allowing to also model the class of ultra hot-Jupiters, with equilibrium temperatures $T_{\mathrm{eq}}\gtrsim 2000$ K. Radiative transfer results were tested by cross-verifying the low- and high-resolution implementation of petitRADTRANS, and benchmarked with the petitCODE, which itself is also benchmarked to the ATMO and Exo-REM codes. We successfully carried out test retrievals of synthetic JWST emission and transmission spectra (for the hot Jupiter TrES-4b, which has a $T_{\mathrm{eq}}$ of $\sim$ 1800 K). The code is publicly available at http://gitlab.com/mauricemolli/petitRADTRANS, and its documentation can be found at https://petitradtrans.readthedocs.io.

17 pages, 7 figures, published in A&A

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Cited by in corpus (123)

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• The ESO SupJup Survey IV. Unveiling the carbon isotope ratio of GQ Lup B and its host star
• A Framework for Characterizing Transmission Spectra of Exoplanets with Circumplanetary Rings
• Large Interferometer For Exoplanets (LIFE): XIII. The Value of Combining Thermal Emission and Reflected Light for the Characterization of Earth Twins
• Large Interferometer For Exoplanets (LIFE): IX. Assessing the Impact of Clouds on Atmospheric Retrievals at Mid-Infrared Wavelengths with a Venus-Twin Exoplanet
• Understanding the atmospheric properties and chemical composition of the ultra-hot Jupiter HAT-P-7b: III. Changing ionisation and the emergence of an ionosphere
• Hot Jupiter Atmospheric Flows at High Resolution
• Rotation and Abundances of the Benchmark Brown Dwarf HD 33632 Ab from Keck/KPIC High-resolution Spectroscopy
• High-resolution Emission Spectroscopy of the Ultrahot Jupiter KELT-9b: Little Variation in Day- and Nightside Emission Line Contrasts
• Peering above the clouds of the warm Neptune GJ 436b with CRIRES+
• The PEPSI Exoplanet Transit Survey. III: The detection of FeI, CrI and TiI in the atmosphere of MASCARA-1 b through high-resolution emission spectroscopy
• Atmospheric characterization of the super-Jupiter HIP 99770 b with KPIC
• VLTI/GRAVITY Observations and Characterization of the Brown Dwarf Companion HD 72946 B
• Hot exoplanetary atmospheres in 3D
• Properties of Sub-Neptune Atmospheres: TOI-270 System
• Detection of TiO and VO in the atmosphere of WASP-121b and Evidence for its temporal variation
• H${}_2$-dominated Atmosphere as an Indicator of Second-generation Rocky White Dwarf Exoplanets
• Polycyclic Aromatic Hydrocarbons in Exoplanet Atmospheres I. Thermochemical Equilibrium Models
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• PDS 70b Shows Stellar-like Carbon-to-oxygen Ratio
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• ACCESS: Tentative detection of H${}_2$O in the ground-based optical transmission spectrum of the low-density hot Saturn HATS-5b
• Radiative Transfer and Inversion codes for characterizing planetary atmospheres: an overview
• Can Isotopologues Be Used as Biosignature Gases in Exoplanet Atmospheres?
• Can Carbon Fractionation Provide Evidence for Aerial Biospheres in the Atmospheres of Temperate Sub-Neptunes?
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• Surface pressure impact on nitrogen-dominated USP super-Earth atmospheres
• Atmospheric composition of WASP-85Ab with ESPRESSO/VLT observations
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• SVEEEETIES: Singular vector expansion to estimate Earth-like exoplanet temperatures from infrared emission spectra
• Transmission spectroscopy of WASP-7 b with UVES -- Detection of Na I D${}_2$ and tentative D${}_1$ line absorption
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• TelescopeML -- I. An End-to-End Python Package for Interpreting Telescope Datasets through Training Machine Learning Models, Generating Statistical Reports, and Visualizing Results
• The effect of a biosphere on the habitable timespan of stagnant-lid planets and implications for the atmospheric spectrum
• CARMENES detection of the CaII infrared triplet and possible evidence of HeI in the atmosphere of WASP-76b
• Refining the Masses and Radii of the Star Kepler-33 and its Five Transiting Planets
• All along the line of sight: a closer look at opening angles and absorption regions in the atmospheres of transiting exoplanets