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Detection of Atomic Chlorine in Io's Atmosphere with HST/GHRS

Lori M. Feaga·Melissa A. McGrath·Paul D. Feldman·Darrell F. Strobel
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Abstract

We report the detection of atomic chlorine emissions in the atmosphere of Io using Hubble Space Telescope observations with the Goddard High Resolution Spectrograph (GHRS). The Cl I 1349 A dipole allowed and Cl I] 1386 A forbidden transition multiplets are detected at a signal to noise ratio (SNR) of 6 and 10, respectively, in a combined GHRS spectrum acquired from 1994 through 1996. Oxygen and sulfur emissions are simultaneously detected with the chlorine which allows for self-consistent abundance ratios of chlorine to these other atmospheric species. The disk averaged ratios are: Cl/O = 0.017 +/- 0.008, Cl/S = 0.10 +/- 0.05, and S/O = 0.18 +/- 0.08. We also derive a geometric albedo of 1.0 +/- 0.4 % for Io at 1335 A assuming an SO2 atmospheric column density of 1x10^{16} cm^{-2}.

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Lori M. Feaga, Melissa A. McGrath, Paul D. Feldman, Darrell F. Strobel. 2004-04-26. Detection of Atomic Chlorine in Io's Atmosphere with HST/GHRS. https://doi.org/10.1086/421862

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