A new astrobiological model of the atmosphere of Titan

Abstract

We present results of an investigation into the formation of nitrogen-bearing molecules in the atmosphere of Titan. We extend a previous model (Li et al. 2015, 2016) to cover the region below the tropopause, so the new model treats the atmosphere from Titan's surface to an altitude of 1500 km. We consider the effects of condensation and sublimation using a continuous, numerically stable method. This is coupled with parameterized treatments of the sedimentation of the aerosols and their condensates, and the formation of haze particles. These processes affect the abundances of heavier species such as the nitrogen-bearing molecules, but have less effect on the abundances of lighter molecules. Removal of molecules to form aerosols also plays a role in determining the mixing ratios, in particular of HNC, HC3N and HCN. We find good agreement with the recently detected mixing ratios of C2H5CN, with condensation playing an important role in determining the abundance of this molecule below 500 km. Of particular interest is the chemistry of acrylonitrile (C2H3CN) which has been suggested by Stevenson et al. (2015) as a molecule that could form biological membranes in an oxygen-deficient environment. With the inclusion of haze formation we find good agreement of our model predictions of acrylonitrile with the available observations.

17 pages, 6 figures, Accepted by ApJ

References in corpus (4)

• Photolytically generated aerosols in the mesosphere and thermosphere of Titan
• Ethyl cyanide on Titan: Spectroscopic detection and mapping using ALMA
• ALMA measurements of the HNC and HC${}_3$N distributions in Titan's atmosphere
• Upper limits for undetected trace species in the stratosphere of Titan

Cited by in corpus (13)

• The Composition and Chemistry of Titan's Atmosphere
• Detection of Cyclopropenylidene on Titan with ALMA
• HCN production in Titan's Atmosphere: Coupling quantum chemistry and disequilibrium atmospheric modeling
• Material Properties of Organic Liquids, Ices, and Hazes on Titan
• Low temperature formation of pyridine and (iso)quinoline via neutral neutral reactions
• The Fate of Simple Organics on Titan's Surface: A Theoretical Perspective
• Multilayer hazes over Saturn's hexagon from Cassini ISS limb images
• Experimental Characterization of the Pyridine:Acetylene Co-crystal and Implications for Titan's Surface
• Retrieval of Chemical Abundances in Titan's Upper Atmosphere from Cassini UVIS Observations with Pointing Motion
• Variability in Titan's Mesospheric HCN and Temperature Structure as Observed by ALMA
• TRAPPIST-1h as an Exo-Titan. I. The Role of Assumptions about Atmospheric Parameters in Understanding an Exoplanet Atmosphere
• Piercing through the Haze: Characterizing Titan-like terrestrial exoplanets with JWST
• Hydrocarbon complexity and photochemical shielding of prebiotic feedstock molecules in exoplanet atmospheres