arXiv subjects

D. R. Müller

Publications and source records attributed to D. R. Müller.

3 recordsLinked to original sources

arXiv2026

Nitrogen- and nitrogen-oxygen-bearing organic molecules in comet 67P/Churyumov-Gerasimenko: An untargeted investigation

Comets provide a unique window into the history of the Solar System as they carry some of the best-preserved material and make it available to in situ exploration. A milestone in comet studies was the European Space Agency's Rosetta mission, which, for the first time, rendezvoused with a comet, namely 67P/Churyumov-Gerasimenko (67P), and studied it from a close range for two years. Amongst other unexpected insights, data from this mission show that comets contain a surprisingly large portion of organics, both in the refractory and the icy phases. For this work, we evaluated high-resolution mass spectra collected in comet 67P's inner coma by Rosetta's ROSINA-Double Focusing Mass Spectrometer (DFMS). In unprecedented detail, we investigated the N- and NO-bearing cometary complex organic molecules (COMs) of the general sum formula CnHmN and CnHmNO, where n and m are the stoichiometric coefficients of carbon and hydrogen. Our discussion-driven approach combines the empirical concept of Occam's razor with knowledge from studies of relevant astrophysical environments and constraints expected from naive bottom-up assembly of molecules. We present an exemplary minimal and non-unique set of molecules needed to explain the DFMS observations. While this set might not capture the full organic diversity, but rather its lower limit, it identifies many N- and NO-bearing COMs with reasonable certainty, while excluding others, potentially informing future observational campaigns, and hence contributes to the exploration of the origin and evolution of organic complexity in space. Among the key results is strong evidence for an abundant presence of heterocycles as well as substantial alkylation of both cyclic and acyclic species. These findings align well with reports on soluble organic matter in meteorites and asteroids and ...

astro-ph.EP↗

arXiv2023

Oxygen-bearing organic molecules in comet 67P's dusty coma: first evidence for abundant heterocycles

The puzzling complexity of terrestrial biomolecules is driving the search for complex organic molecules in the Interstellar Medium (ISM) and serves as a motivation for many in situ studies of reservoirs of extraterrestrial organics from meteorites and interplanetary dust particles (IDPs) to comets and asteroids. Comet 67P/Churyumov-Gerasimenko (67P) -- the best-studied comet to date -- has been visited and accompanied for two years by the European Space Agency's Rosetta spacecraft. Around 67P's perihelion and under dusty conditions, the high-resolution mass spectrometer on board provided a spectacular glimpse into this comet's chemical complexity. For this work, we analyzed in unprecedented detail the O-bearing organic volatiles. In a comparison of 67P's inventory to molecules detected in the ISM, in other comets, and in Soluble Organic Matter (SOM) extracted from the Murchison meteorite, we also highlight the (pre)biotic relevance of different chemical groups of species. We report first evidence for abundant extraterrestrial O-bearing heterocycles (with abundances relative to methanol often on the order of 10% with a relative error margin of 30-50%) and various representatives of other molecule classes such as carboxylic acids and esters, aldehydes, ketones, and alcohols. Like with the pure hydrocarbons, some hydrogenated forms seem to be dominant over their dehydrogenated counterparts. An interesting example is tetrahydrofuran (THF) as it might be a more promising candidate for searches in the ISM than the long-sought furan itself. Our findings not only support and guide future efforts to investigate the origins of chemical complexity in space, but also they strongly encourage studies of, e.g., the ratios of unbranched vs. branched and hydrogenated vs. dehydrogenated species in astrophysical ice analogs in the laboratory as well as by modeling.

astro-ph.EP↗

arXiv2022

Abundant ammonium hydrosulphide embedded in cometary dust grains

Ammonium hydrosulphide has long since been postulated to exist at least in certain layers of the giant planets. Its radiation products may be the reason for the red colour seen on Jupiter. Several ammonium salts, the products of NH3 and an acid, have previously been detected at comet 67P/Churyumov-Gerasimenko. The acid H2S is the fifth most abundant molecule in the coma of 67P followed by NH3. In order to look for the salt NH4+SH-, we analysed in situ measurements from the Rosetta/ROSINA Double Focusing Mass Spectrometer during the Rosetta mission. NH3 and H2S appear to be independent of each other when sublimating directly from the nucleus. However, we observe a strong correlation between the two species during dust impacts, clearly pointing to the salt. We find that NH4+SH- is by far the most abundant salt, more abundant in the dust impacts than even water. We also find all previously detected ammonium salts and for the first time ammonium fluoride. The amount of ammonia and acids balance each other, confirming that ammonia is mostly in the form of salt embedded into dust grains. Allotropes S2 and S3 are strongly enhanced in the impacts, while H2S2 and its fragment HS2 are not detected, which is most probably the result of radiolysis of NH4+SH-. This makes a prestellar origin of the salt likely. Our findings may explain the apparent depletion of nitrogen in comets and maybe help to solve the riddle of the missing sulphur in star forming regions.

astro-ph.EP↗