Krypton isotopes and noble gas abundances in the coma of comet 67P/Churyumov-Gerasimenko

TL;DR

This study analyzes noble gas isotopes in comet 67P's coma, revealing isotopic compositions close to solar for krypton and xenon, but with argon depletion, indicating exotic xenon components.

Contribution

It provides the first detailed isotopic analysis of krypton in comet 67P, highlighting the presence of exotic xenon components and isotopic deviations from solar abundances.

Findings

Krypton isotopic composition is close to solar.

Argon is depleted relative to krypton and xenon.

Exotic xenon component is suggested in the comet.

Abstract

The ROSINA mass spectrometer DFMS on board ESA's Rosetta spacecraft detected the major isotopes of the noble gases argon, krypton, and xenon in the coma of comet 67P/Churyumov-Gerasimenko. Earlier, it has been shown that xenon exhibits an isotopic composition distinct from anywhere else in the solar system. However, argon isotopes, within error, were shown to be consistent with solar isotope abundances. This discrepancy suggested an additional exotic component of xenon in comet 67P/Churyumov-Gerasimenko. Here we show that also krypton exhibits an isotopic composition close to solar. Furthermore, we found a depletion compared to solar of argon with respect to krypton and of krypton with respect to xenon, which is a necessity to postulate an addition of exotic xenon in the comet.