Ortho-to-para abundance ratios of NH2in 26 comets: implications for the real meaning of OPRs

• DOI: 10.1093/mnras/stw2298
• Publication Date: 2016-09-12T20:07:56Z
• Authors: Yoshiharu Shinnaka; Hideyo Kawakita; Emmanuël Jehin; Alice Decock; Damien Hutsemékers; Jean Manfroid
• Keywords: Interstellar comet

Abundance ratios of nuclear-spin isomers for cometary molecules having identical protons, such as water and ammonia, have been measured discussed from the viewpoint that they are primordial characters in comet. In case its ortho-to-para abundance ratio (OPR) is usually estimated OPRs NH2 because difficulty measuring OPR ammonia directly. We report our survey 26 comets. A weighted mean comets 1.12 ± 0.01 no significant difference found between Oort Cloud Jupiter-family These values correspond to ∼30 K temperatures. The probably reflect physicochemical conditions coma, rather than molecular formation or condensation pre-solar cloud/the solar nebula, based on comparison (and temperatures) with those water, 14N/15N D/H water. could be reset a weights solid phase modified by interactions protonated ions like H3O+, clusters (H2O)n, ice grains, paramagnetic impurities (such O2 grains) inner coma gas. Relationship clue understanding real meaning OPRs.