A chemical model for the atmosphere of hot Jupiters

By O. Venot, E. H'ebrard, M. Agúndez, M. Dobrijevic, F. Selsis, F. Hersant, N. Iro, R. Bounaceur. 2012

196 citations recorded by the source corpus.

Our purpose is to release a chemical network, and the associated rate coefficients, developed for the temperature and pressure range relevant to hot Jupiters atmospheres. Using this network, we study the vertical atmospheric composition of the two hot Jupiters (HD209458b, HD189733b) with a model that includes photolyses and vertical mixing and we produce synthetic spectra. The chemical scheme is derived from applied combustion models that have been methodically validated over a range of temperatures and pressures typical of the atmospheric layers influencing the observations of hot Jupiters. We compare the predictions obtained from this scheme with equilibrium calculations, with different schemes available in the literature that contain N-bearing species and with previously published photochemical models. Compared to other chemical schemes that were not subjected to the same systematic validation, we find significant differences whenever non-equilibrium processes take place. The deviations from the equilibrium, and thus the sensitivity to the network, are more important for HD189733b, as we assume a cooler atmosphere than for HD209458b. We found that the abundances of NH3 and HCN can vary by two orders of magnitude depending on the network, demonstrating the importance of comprehensive experimental validation. A spectral feature of NH3 at 10.5$\mu$m is sensitive to these abundance variations and thus to the chemical scheme. Due to the influence of the kinetics, we recommend the use of a validated scheme to model the chemistry of exoplanet atmospheres. Our network is robust for temperatures within 300-2500K and pressures from 10mbar up to a few hundreds of bars, for species made of C,H,O,N. It is validated for species up to 2 carbon atoms and for the main nitrogen species.

Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/8840fb7e981a74f49b70867b2dc4ab6df6c87bb2

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Citations in the corpus

ExoMol line lists - III. An improved hot rotation-vibration line list for HCN and HNC (2013, background): “HCN is likely to feature in carbon rich atmospheres, especially so when disequilibrium effects are taken into account (Madhusudhan 2012; Venot et al. 2012; Moses et al. 2013).”
Retrieving scattering clouds and disequilibrium chemistry in the atmosphere of HR 8799e (2020, result): “This treatment has been further verified by comparing to the results of the reaction network by Venot et al. (2012, 2015) in Baudino et al. (2017).”
CHARACTERIZING TRANSITING EXOPLANET ATMOSPHERES WITH JWST (2015, background): “Disequilibrium Chemistry Disequilibrium processes are likely to play a role in sculpting the molecular abundances in exoplanet atmospheres (Liang et al. 2003; Zahnle et al. 2009; Line et al. 2010; Moses et al. 2011; Line et al. 2011; Venot et al. 2012; Agúndez et al. 2014; Hu et al. 2013).”
Equilibrium chemistry down to 100 K (2017, background): “However, recent kinetic chemical models (Visscher et al. 2006, 2010; Zahnle et al. 2009; Line et al. 2010; Moses et al. 2011; Kopparapu et al. 2012; Venot et al. 2012) have shown that in hot exoplanet atmospheres (T >∼ 1200 K), the chemical timescales are in fact quite short, and hence…”
 ?> -REx. II. RETRIEVAL OF EMISSION SPECTRA (2015, result): “Whereas these values differ from previous analyses, we find them significantly closer to the chemical model predictions of HD189733b (e.g. Line et al. 2010; Venot et al. 2012; Moses et al. 2013).”
3D mixing in hot Jupiters atmospheres. I. Application to the day/night cold trap in HD 209458b (2013, background): “…vertical structure of hot Jupiter atmospheres, with the 3D dynamics parameterized as vertical eddy diffusion with a specified diffusivity (e.g Spiegel et al. 2009; Zahnle et al. 2009b,a; Youdin & Mitchell 2010; Line et al. 2010, 2011; Madhusudhan et al. 2011; Moses et al. 2011; Venot et al. 2012).”
VULCAN: An Open-source, Validated Chemical Kinetics Python Code for Exoplanetary Atmospheres (2016, methodology): “…photochemical kinetics (Kopparapu, Kasting & Zahnle 2012; Line et al. 2011; Visscher & Moses 2011; Moses et al. 2011; Hu, Seager & Bains 2012; Moses et al. 2013a,b; Line & Yung 2013; Agúndez et al. 2014; Zahnle & Marley 2014; Hu, Seager & Yung 2015; Venot et al. 2012, 2015; Rimmer & Helling 2016).”
DETECTION OF AN ATMOSPHERE AROUND THE SUPER-EARTH 55 CANCRI E (2015, methodology): “We used the same chemical scheme implemented in Venot et al. (2012) to produce vertical abundance profiles for 55 Cancri e, assuming a solar C/O ratio and a C/O ratio of 1.1.”