Water Ortho-to-Para ratio in the coma of comet 67P/Churyumov-Gerasimenko

Y. -C. Cheng, D. Bockelée-Morvan, M. Roos-Serote +9

Abundance ratios of the nuclear-spin isomers of H${}_2$O and NH${}_3$ have been measured in about two dozen comets, with a mean value corresponding to a nuclear-spin temperature of $\s…