The detection of benzene in Saturn's upper atmosphere

• Published in: Geophysical research letters Vol. 43; no. 15; pp. 7895 - 7901
• Main Authors: Koskinen, T. T., Moses, J. I., West, R. A., Guerlet, S., Jouchoux, A.
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 16-08-2016; American Geophysical Union
• Subjects: Aromatic compounds; Atmosphere; Atmospheric chemistry; Atmospheric models; Benzene; Cassini mission; Chemistry; Condensates; Condensation; Constraint modelling; Detection; Haze; High altitude; Hydrocarbons; Imaging; Imaging techniques; Ion chemistry; Latitude; Night; Northern Hemisphere; Opacity; Photochemicals; Photochemistry; Poles; Pollution detection; Polycyclic aromatic hydrocarbons; Profiles; Saturn; Saturn atmosphere; Saturn stratosphere; Saturn upper atmosphere; Sciences of the Universe; Spring; Stratosphere; Ultraviolet astronomy; Upper atmosphere; Vertical profiles; Saturn; photochemistry
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2016GL070000

The stratosphere of Saturn contains a photochemical haze that appears thicker at the poles and may originate from chemistry driven by the aurora. Models suggest that the formation of hydrocarbon haze is initiated at high altitudes by the production of benzene, which is followed by the formation of heavier ring polycyclic aromatic hydrocarbons. Until now there have been no observations of hydrocarbons or photochemical haze in the production region to constrain these models. We report the first vertical profiles of benzene and constraints on haze opacity in the upper atmosphere of Saturn retrieved from Cassini Ultraviolet Imaging Spectrograph stellar occultations. We detect benzene at several different latitudes and find that the observed abundances of benzene can be produced by solar‐driven ion chemistry that is enhanced at high latitudes in the northern hemisphere during spring. We also detect evidence for condensation and haze at high southern latitudes in the polar night.
Key Points
We present the first detections of benzene and hydrocarbon haze in their production region in Saturn's upper atmosphere
The observed benzene abundances can be explained by solar‐driven ion chemistry that is enhanced at high latitudes in the north