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Published August 2006 | public
Journal Article

Deuterium chemistry and airglow in the jovian thermosphere

Abstract

We present a detailed study of the distribution of key deuterated species (viz., atomic D and HD) and the associated deuterium Lyman-α airglow in the jovian thermosphere. The reactions that appear to govern the abundances of these deuterated species are used in conjunction with C_2-chemistry in a 1-D photochemical-diffusion model. While the D abundance is mainly sensitive to H densities and the vibrational temperature profile, the D vertical distribution also depends on other parameters such as eddy mixing and the uncertain values of some of the reaction rate constants. We consider different scenarios by varying several parameters controlling the D distribution in the thermosphere. A radiative transfer model with coupling of the H and D Lyman-α lines is employed to obtain line profiles and total intensities at disk center for these scenarios. This allows a comparison of the impact of various parameters on the jovian D Lyman-α emission. A consequence of these chemical processes in the jovian thermosphere is the formation of CH_2D, CH_3D, and C_2H_5D, and other deuterated species. We also discuss the source of these deuterated hydrocarbons and their abundance. We find that HD vibrational chemistry impacts D in the thermosphere, CH_3D and C_2H_5D are vibrationally enhanced in the thermosphere, and variations in abundance of CH_3D and C_2H_5D in the thermosphere may reflect dynamical activity (i.e., K_h) in the jovian upper atmosphere. An observing program dedicated to providing such measurements of these testable phenomena would provide further insight into the synergistic coupling between chemistry, energetics and airglow in the jovian upper atmosphere.

Additional Information

© 2005 Elsevier Inc. Received 23 February 2004; revised 20 September 2005. Available online 21 June 2006. C.D. Parkinson thanks G.R. Gladstone of SWRI for the use of his radiative transfer code. L. Ben Jaffel and C.D. Parkinson thank CNRS and INSU for continuing support through the PNP Program. C.D. Parkinson acknowledges that some of this work was supported by the National Aeronautics and Space Administration through the NASA Astrobiology Institute under Cooperative Agreement No. CAN-00-OSS-01 and issued through the Office of Space Science. J. McConnell thanks the Natural Sciences and Engineering Research Council of Canada for continuing support. Part of this work was done at York University. Y.L. Yung and A.Y.-T. Lee acknowledge support by NASA Grant NASA5-13296 to the California Institute of Technology.

Additional details

Created:
August 22, 2023
Modified:
October 17, 2023