Ethyl cyanide on titan: Spectroscopic detection and mapping using alma

M. A. Cordiner*, M. Y. Palmer, C. A. Nixon, P. G.J. Irwin, N. A. Teanby, S. B. Charnley, M. J. Mumma, Z. Kisiel, J. Serigano, Y. J. Kuan, Y. L. Chuang, K. S. Wang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

55 Citations (Scopus)

Abstract

We report the first spectroscopic detection of ethyl cyanide (C2H5CN) in Titan's atmosphere, obtained using spectrally and spatially resolved observations of multiple emission lines with the Atacama Large Millimeter/ submillimeter Array (ALMA). The presence of C2H5CN in Titan's ionosphere was previously inferred from Cassini ion mass spectrometry measurements of C2H5CNH+. Here we report the detection of 27 rotational lines from C2H5CN (in 19 separate emission features detected at >3s confidence) in the frequency range 222-241 GHz. Simultaneous detections of multiple emission lines from HC3N, CH3CN, and CH3CCH were also obtained. In contrast to HC3N, CH3CN, and CH3CCH, which peak in Titan's northern (spring) hemisphere, the emission from C2H5CN is found to be concentrated in the southern (autumn) hemisphere, suggesting a distinctly different chemistry for this species, consistent with a relatively short chemical lifetime for C2H5CN. Radiative transfer models show that C2H5CN is most concentrated at altitudes ≳200 km, suggesting production predominantly in the stratosphere and above.

Original languageEnglish
Article numberL14
JournalAstrophysical Journal Letters
Volume800
Issue number1
DOIs
Publication statusPublished - 2015 Feb 10

Keywords

  • Planets and satellites: atmospheres
  • Planets and satellites: individual (Titan)
  • Techniques: imaging spectroscopy
  • Techniques: interferometric

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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