Although we cannot identify individual molecules in the complex gas mixture that makes up for the cometary coma, we are able to characterize for the first time the larger organic species that bridge the small volatiles and the macromolecular matter observed in 67P’s dust by the Rosetta secondary ion mass spectrometer COSIMA (Fray et al. Larger species tend to expose a lower degree of saturation and the H/C ratio seems to approach that of highly unsaturated insoluble organic matter (IOM), cf., e.g., Sandford 2008. Due to the problem of isomerism and the lack of reference data, we chose to follow a statistical approach for our analysis. Probably due to sublimation of molecules from ejected and heated-up dust grains, ROSINA/DFMS registered many signals above m/z=70. On this day, the comet was close to its perihelion and the dust activity, as seen by the OSIRIS camera (Vincent et al. Here, we will present preliminary results from the first comprehensive analysis of a full data set (from m/z=12 to m/z=140) collected on August 3, 2015. (2019) have reported tentative detections of some heavier species like benzoic acid or naphthalene, spectra of m/z>70 have not been investigated systematically.
Manual fitting of individual spectra allows to resolve pure hydrocarbon from heteroatom-bearing species also in the higher mass-range of the instrument, up to mass-to-charge (m/z) ratios of 140.2007) – delivered data which contains information about the transition region between volatiles and macromolecular matter. However, the Double Focusing Mass Spectrometer (DFMS) – part of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA Balsiger et al. Thanks to ESA’s Rosetta mission, the neutral coma of comet 67P/Churyumov-Gerasimenko (67P hereafter) has been analyzed in great spatial and temporal detail, e.g., by Rubin et al.
Small and volatile molecules are the most abundant constituents of a comet’s neutral coma.
0 kommentar(er)
