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

De Keyser, Johan; Gombosi, Tamas I.; Berthelier, Jean-Jacques +14 more

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^-) a…

Infrared detection of aliphatic organics on a cometary nucleus

Bellucci, G.; Carlson, R. W.; Fornasier, S. +28 more

The European Space Agency's Rosetta mission¹ has acquired unprecedented measurements of the surface of the nucleus of comet 67P/Churyumov-Gerasimenko (hereafter, 67P), the composition of which, as determined by in situ and remote-sensing instruments, including the VIRTIS instrument², seems to be an assemblage of ices, mineral…

Far-ultraviolet aurora identified at comet 67P/Churyumov-Gerasimenko

Altwegg, K.; Feldman, P. D.; Carr, C. +14 more

Having a nucleus darker than charcoal, comets are usually detected from Earth through the emissions from their coma. The coma is an envelope of gas that forms through the sublimation of ices from the nucleus as the comet gets closer to the Sun. In the far-ultraviolet portion of the spectrum, observations of comae have revealed the presence of atom…