Desai, RT;
Coates, AJ;
Wellbrock, A;
Vuitton, V;
Crary, FJ;
González-Caniulef, D;
Shebanits, O;
... Sittler, EC; + view all
(2017)
Carbon chain anions and the growth of complex organic molecules in Titan's ionosphere.
The Astrophysical Journal Letters
, 844
(2)
10.3847/2041-8213/aa7851.
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Abstract
Cassini discovered a plethora of neutral and ionized molecules in Titan's ionosphere including, surprisingly, anions and negatively charged molecules extending up to 13,800 u q−1. In this Letter, we forward model the Cassini electron spectrometer response function to this unexpected ionospheric component to achieve an increased mass resolving capability for negatively charged species observed at Titan altitudes of 950–1300 km. We report on detections consistently centered between 25.8 and 26.0 u q−1 and between 49.0–50.1 u q−1 which are identified as belonging to the carbon chain anions, CN−/C3N− and/or C2H−/C4H−, in agreement with chemical model predictions. At higher ionospheric altitudes, detections at 73–74 u q−1 could be attributed to the further carbon chain anions C5N−/C6H− but at lower altitudes and during further encounters extend over a higher mass/charge range. This, as well as further intermediary anions detected at >100 u, provide the first evidence for efficient anion chemistry in space involving structures other than linear chains. Furthermore, at altitudes below <1100 km, the low-mass anions (<150 u q−1) were found to deplete at a rate proportional to the growth of the larger molecules, a correlation that indicates the anions are tightly coupled to the growth process. This study adds Titan to an increasing list of astrophysical environments where chain anions have been observed and shows that anion chemistry plays a role in the formation of complex organics within a planetary atmosphere as well as in the interstellar medium.
| Type: | Article |
|---|---|
| Title: | Carbon chain anions and the growth of complex organic molecules in Titan's ionosphere |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.3847/2041-8213/aa7851 |
| Publisher version: | http://dx.doi.org/10.3847/2041-8213/aa7851 |
| Language: | English |
| Additional information: | Copyright © 2017. The American Astronomical Society. All rights reserved. Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. |
| Keywords: | astrobiology, astrochemistry, ISM: molecules, planets and satellites: atmospheres, planets and satellites: individual (Titan) |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1568197 |
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Carbon chain anions and the growth of complex organic molecules in Titan's ionosphere. (deposited 09 Jul 2017 00:39)
- Carbon chain anions and the growth of complex organic molecules in Titan's ionosphere. (deposited 04 Aug 2017 11:30) [Currently Displayed]
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