Non-detection of hydrogen cyanide on jupiter

Bruno Bézard, Caitlin Griffith, John Lacy, Tobias Owen

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


High spectral resolution observations of Jupiter performed at the NASA/Infrared Telescope Facility near 13.5 μm are presented. Two spectral ranges including the R(7) and R(11) lines of the v2 band of HCN were observed at high signal-to-noise. No evidence for HCN absorption in excess of 2% of the continuum was found, in contrast to the report by Tokunaga et al. (1981, Icarus 48, 283-289). An upper limit on the tropospheric HCN mixing ratio of 1 × 10-9 was derived, assuming a uniform value up to the tropopause. When HCN condensation in the upper troposphere is taken into account, only a looser upper limit around 1.2 × 10-8 can be set on the deep mixing ratio. The lack of emission cores at the position of the HCN lines provides an upper limit of 2 × 10-4 cm-amagat on the HCN column density in the stratosphere (corresponding to a maximum average mixing ratio of 8 × 10-10 above condensation level). A critical reanalysis of Tokunaga et al.'s observations is finally presented, leading to the conclusion that the previously reported detection of HCN is questionable.

Original languageEnglish (US)
Pages (from-to)384-391
Number of pages8
Issue number2
StatePublished - Dec 1995

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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