ETHYL CYANIDE ON TITAN: SPECTROSCOPIC DETECTION AND MAPPING USING ALMA
| Autor: | Yi-Jehng Kuan, Kuo-Song Wang, Michael J. Mumma, Patrick G. J. Irwin, Zbigniew Kisiel, M. Y. Palmer, Nicholas A Teanby, Conor A. Nixon, Joseph Serigano, Y. L. Chuang, Martin A. Cordiner, Steven B. Charnley |
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| Rok vydání: | 2015 |
| Předmět: |
Earth and Planetary Astrophysics (astro-ph.EP)
FOS: Physical sciences Astronomy and Astrophysics Astrophysics atmospheres [planets and satellites] Mass spectrometry Submillimeter Array individual (Titan) [planets and satellites] interferometric [techniques] Ion Atmosphere symbols.namesake Space and Planetary Science astro-ph.EP symbols Radiative transfer Emission spectrum Ionosphere Titan (rocket family) imaging spectroscopy [– techniques] Astrophysics - Earth and Planetary Astrophysics |
| Zdroj: | Cordiner, M A, Palmer, M Y, Nixon, C A, Irwin, P G J, Teanby, N A, Charnley, S B, Mumma, M J, Kisiel, Z, Serigano, J, Kuan, Y-J, Chuang, Y-L & Wang, K-S 2015, ' ETHYL CYANIDE ON TITAN : SPECTROSCOPIC DETECTION AND MAPPING USING ALMA ', Astrophysical Journal Letters, vol. 800, no. 1, pp. 1-7 . https://doi.org/10.1088/2041-8205/800/1/L14 |
| ISSN: | 2041-8213 |
| Popis: | We report the first spectroscopic detection of ethyl cyanide (C$_2$H$_5$CN) 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 C$_2$H$_5$CN in Titan's ionosphere was previously inferred from Cassini ion mass spectrometry measurements of C$_2$H$_5$CNH$^+$. Here we report the detection of 27 rotational lines from C$_2$H$_5$CN (in 19 separate emission features detected at $>3\sigma$ confidence), in the frequency range 222-241 GHz. Simultaneous detections of multiple emission lines from HC$_3$N, CH$_3$CN and CH$_3$CCH were also obtained. In contrast to HC$_3$N, CH$_3$CN and CH$_3$CCH, which peak in Titan's northern (spring) hemisphere, the emission from C$_2$H$_5$CN 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 C$_2$H$_5$CN. Radiative transfer models show that most of the C$_2$H$_5$CN is concentrated at altitudes 300-600 km, suggesting production predominantly in the mesosphere and above. Vertical column densities are found to be in the range (2-5)$\times10^{14}$ cm$^{-2}$. Comment: Published in 2015, ApJL, 800, L14 |
| Databáze: | OpenAIRE |
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