Evidence of ammonium salts in comet 67P as explanation for the nitrogen depletion in cometary comae

Altwegg, Kathrin; Balsiger, Hans; Hänni, Nora; Rubin, Martin; Schuhmann, Markus; Schroeder, Isaac; Sémon, Thierry; Wampfler, Susanne; Berthelier, Jean-Jacques; Briois, Christelle; Combi, Mike; Gombosi, Tamas I.; Cottin, Hervé; De Keyser, Johan; Dhooghe, Frederik; Fiethe, Björn; Fuselier, Steven A. (2020). Evidence of ammonium salts in comet 67P as explanation for the nitrogen depletion in cometary comae. Nature astronomy, 4(5), pp. 533-540. Springer Nature 10.1038/s41550-019-0991-9

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Cometary comae are generally depleted in nitrogen. The main carriers for volatile nitrogen in comets are NH₃ and HCN. It is known that ammonia readily combines with many acids, such as HCN, HNCO and HCOOH, encountered in the interstellar medium as well as in cometary ice to form ammonium salts (NH₄⁺X⁻) at low temperatures. Ammonium salts, which can have a substantial role in prebiotic chemistry, are hard to detect in space as they are unstable in the gas phase and their infrared signature is often hidden by thermal radiation or by, for example, OH in minerals. Here we report the presence of all possible sublimation products of five different ammonium salts in the comet 67P/Churyumov–Gerasimenko measured by the ROSINA instrument onboard Rosetta. The relatively high sublimation temperatures of the salts leads to an apparent lack of volatile nitrogen in the coma. This then also explains the observed trend of higher NH₃/H₂O ratios with decreasing perihelion distances in comets.

Item Type:

Journal Article (Original Article)


08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences
08 Faculty of Science > Physics Institute
10 Strategic Research Centers > Center for Space and Habitability (CSH)

UniBE Contributor:

Hänni, Nora Phillys, Rubin, Martin, Schuhmann, Markus, Schroeder I, Isaac Raedwald Hans Garfield, Sémon, Thierry, Wampfler, Susanne


500 Science > 520 Astronomy
500 Science > 530 Physics
600 Technology > 620 Engineering




Springer Nature




Danielle Zemp

Date Deposited:

06 May 2020 13:41

Last Modified:

02 Mar 2023 23:33

Publisher DOI:






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