On the Abiotic Origin of Dimethyl Sulfide: Discovery of Dimethyl Sulfide in the Interstellar Medium

The Astrophysical Journal Letters, Journal Year: 2025, Volume and Issue: 980(2), P. L37 - L37

Published: Feb. 18, 2025

Abstract Following the discovery of dimethyl sulfide (DMS; CH 3 SCH ) signatures in comet 67P/Churyumov–Gerasimenko, we report first detection this organosulfur species interstellar medium during exploration an ultradeep molecular line survey performed toward Galactic center cloud G+0.693-0.027 with Yebes 40 m and IRAM 30 telescopes. We derive a column density N = (2.6 ± 0.3) × 10 13 cm −2 , yielding fractional abundance relative to H 2 ∼1.9 −10 . This implies that DMS is factor ∼1.6 times less abundant than its structural isomer SH ∼30 O-analog ether (CH OCH cloud, excellent agreement previous results on various O/S pairs. Furthermore, find remarkable resemblance between DMS/CH OH (∼1.7 −3 (∼1.3 ). Although chemistry beyond Earth has yet be fully disclosed, provides conclusive observational evidence efficient abiotic production medium, casting doubt using as reliable biomarker exoplanet science.

Language: Английский

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Overview of desorption parameters of volatile and complex organic molecules

Astronomy and Astrophysics, Journal Year: 2023, Volume and Issue: 676, P. A80 - A80

Published: June 26, 2023

Many molecules observed in the interstellar medium are thought to result from thermal desorption of ices. Parameters such as energy and pre-exponential frequency factor essential describe molecules. Experimental determinations these parameters missing for many molecules, including those found medium. The objective this work is expand number which available, by collecting re-analysing experimental temperature programmed data that present literature. Transition State Theory (TST) used combination with Redhead equation determine parameters. molecular constants (e.g., mass, moment inertia) collected given input. Using Redhead-TST method, 133 have been determined. method provide reliable results agree well determined more rigorous methods. importance using accurately factors simulate profiles emphasised. large amount allows look trends, most important relationship log$_{10}$($\nu$) = 2.65ln($m$) + 8.07, where $\nu$ $m$ mass molecule. allow model help understand changes chemical elemental composition environments.

Language: Английский

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Evidence for Abiotic Dimethyl Sulfide in Cometary Matter

The Astrophysical Journal, Journal Year: 2024, Volume and Issue: 976(1), P. 74 - 74

Published: Nov. 1, 2024

Technological progress related to astronomical observatories such as the recently launched James Webb Space Telescope (JWST) allows searching for signs of life beyond our Solar System, namely in form unambiguous biosignature gases exoplanetary atmospheres. The tentative assignment a $1-2.4\sigma$ spectral feature observed with JWST atmosphere exoplanet K2-18b gas dimethyl sulfide (DMS; sum formula C$_2$H$_6$S) raised hopes that, although controversial, second genesis had been found. Terrestrial atmospheric DMS is exclusively stemming from marine biological activity and no natural abiotic source has identified - neither on Earth nor space. Therefore, considered robust biosignature. Since comets possess pristine inventory complex organic molecules origin, we have searched high-resolution mass spectra collected at comet 67P/Churyumov-Gerasimenko, target European Agency's Rosetta mission, signatures DMS. Previous work reported presence C2H6S signal when was near its equinox but distinction structural isomer ethanethiol remained elusive. Here reassess these evaluate additional data. Based differences electron ionization induced fragmentation pattern two isomers, show that significantly better compatible observations. Deviations between expected intensities are $<1\sigma$, while they $2-4\sigma$. local abundance relative methanol deduced data (0.13$\pm$0.04)%. Our results provide first evidence existence an synthetic pathway cometary matter hence motivate more detailed studies sulfur chemistry analogs. [...]

Language: Английский

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Volatiles in the H2O and CO2 ices of comet 67P/Churyumov–Gerasimenko

Monthly Notices of the Royal Astronomical Society, Journal Year: 2023, Volume and Issue: 526(3), P. 4209 - 4233

Published: Oct. 5, 2023

ABSTRACT European Space Agency’s Rosetta spacecraft at comet 67P/Churyumov–Gerasimenko (67P) was the first mission that accompanied a over substantial fraction of its orbit. On board Orbiter Spectrometer for Ion and Neutral Analysis mass spectrometer suite to measure local densities volatile species sublimating from ices inside comet’s nucleus. Understanding nature these key goal Rosetta. We analysed primary cometary molecules 67P, namely H2O CO2, together with minor almost entire mission. Our investigation reveals abundances highly species, such as CH4 CO, are reproduced by linear combination both CO2 densities. These findings bear similarities laboratory-based temperature-programmed desorption experiments amorphous imply trapped in ices. results do not show presence dominated molecules. Most likely, they were lost due thermal processing 67P’s interior prior deflection inner solar system. Deviations proportions co-released can only be observed before inbound equinox, when still far sun abundance associated outgassing lower. The corresponding is likely seasonal frost, which sublimated re-freezing during previous apparition. on other hand, elevated same time requires further investigation.

Language: Английский

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Complex organosulfur molecules on comet 67P: Evidence from the ROSINA measurements and insights from laboratory simulations

Science Advances, Journal Year: 2023, Volume and Issue: 9(23)

Published: June 7, 2023

The ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) instrument aboard the Rosetta mission revolutionized our understanding of cometary material composition. One Rosetta's key findings is complexity composition comet 67P/Churyumov-Gerasimenko. Here, we used data to analyze dust particles that were volatilized during a event in September 2016 report detection large organosulfur species an increase abundances sulfurous previously detected coma. Our support presence complex sulfur-bearing organics on surface comet. In addition, conducted laboratory simulations show this may have formed from chemical reactions initiated by irradiation mixed ices containing H2S. highlight importance sulfur chemistry precometary materials possibility characterizing other comets small icy bodies using James Webb Space Telescope.

Language: Английский

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Hot Sulfur on the Rocks: The Reaction of Electronically Excited Sulfur Atoms with Water in an Ice-Surface Model

ACS Earth and Space Chemistry, Journal Year: 2025, Volume and Issue: unknown

Published: March 25, 2025

In this contribution, we present a theoretical investigation of the reaction involving atomic sulfur in its first electronically excited state, 1D, and H2O on an ice-surface model. This study is motivated by work Giustini et al. (ACS Earth Space Chem., 2024, 8, 2318), which indicated strong effect presence four additional water molecules S(1D) + compared to pure gas-phase case. Our simulation treats long-range interactions (H-bonds dispersion forces) with ice much more realistic way being based use cluster 18 molecules, thus overcoming limits small used According our results, reacts via two possible mechanisms: (1) addition O atom molecule formation H2OS or (2) insertion into one O–H bonds HOSH. Both HOSH are stabilized energy dissipation rather than isomerizing dissociating products as seen reaction. The interaction surrounding affects entire pathway stabilizing intermediate species, reducing some barriers, impeding only two-product open channel can be produced UV-induced photodissociation various precursor surface interstellar cometary other high-energy processes induced electrons cosmic rays also bulk. Therefore, results help elucidating mysterious chemistry occurring icy mantles grains nuclei. Furthermore, demonstrates that product branching ratios reactions should not uncritically modeling chemistry.

Language: Английский

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The AstroPAH 10 Years of Science Review

Space Science Reviews, Journal Year: 2025, Volume and Issue: 221(4)

Published: May 6, 2025

Language: Английский

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Gas Sources from the Coma and Nucleus of Comet 46P/Wirtanen Observed Using ALMA

The Astrophysical Journal, Journal Year: 2023, Volume and Issue: 953(1), P. 59 - 59

Published: Aug. 1, 2023

Abstract Gas-phase molecules in cometary atmospheres (comae) originate primarily from (1) outgassing by the nucleus, (2) sublimation of icy grains near-nucleus coma, and (3) coma (photo)chemical processes. However, majority gases observed at radio wavelengths have yet to be mapped, so their production/release mechanisms remain uncertain. Here we present observations six molecular species toward comet 46P/Wirtanen, obtained using Atacama Large Millimeter/submillimeter Array during comet’s unusually close (∼0.1 au) approach Earth 2018 December. Interferometric maps HCN, CH 3 OH, CN, H 2 CO, CS, HNC were an unprecedented sky-projected spatial resolution up 25 km, enabling nucleus sources these accurately quantified. The CN distributions are consistent with production direct (or very to) a significant proportion OH originating (at scale length L p = 36 ± 7 km). On other hand, distributed (with values range 550–16,000 km), identities which established. abundances 46P average previously comets, whereas CS relatively low.

Language: Английский

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Deciphering cometary outbursts: linking gas composition changes to trigger mechanisms

Monthly Notices of the Royal Astronomical Society, Journal Year: 2024, Volume and Issue: 529(3), P. 2763 - 2776

Published: Feb. 28, 2024

ABSTRACT Dust and gas outbursts are recurrent cometary phenomena, playing a crucial role in shaping the coma. Proposed outburst trigger mechanisms include cliff collapse, pressure pockets, amorphous-to-crystalline phase transition of water ice; however, underlying processes remain inadequately understood. In this study, we analyse Rosetta/ROSINA data from multiple on comet 67P/Churyumov-Gerasimenko present evolution composition comet’s coma during events. We distinguish two distinct categories comet: water-driven events characterized by rapid (minutes to hours) changes composition, CO2-driven displaying slow, prolonged (hours days) increase highly volatile species. tentatively associate these different patterns with mechanisms. Exposure fresh ice due collapse leads notable enhancement, while most perihelion coincide substantial density increases CO2. propose that originate subsurface gas-filled cavities, whose walls suggested have been sealed earlier refreezing CO2 migrating warmer spots, hence increasing cavity required burst.

Language: Английский

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

Astronomy and Astrophysics, Journal Year: 2023, Volume and Issue: 678, P. A22 - A22

Published: Aug. 18, 2023

The puzzling complexity of terrestrial biomolecules is driving the search for complex organic molecules in interstellar medium (ISM) and serves as a motivation many situ studies reservoirs extraterrestrial organics, from meteorites interplanetary dust particles to comets asteroids. Comet 67P/Churyumov-Gerasimenko (67P), best-studied comet date, has been visited accompanied 2 yr by European Space Agency’s Rosetta spacecraft. Around 67P’s perihelion under dusty conditions, high-resolution mass spectrometer on board provided spectacular glimpse into this comet’s chemical complexity. For work, we analyzed O-bearing volatiles unprecedented detail. Through comparison inventory with detected ISM, other comets, soluble matter extracted Murchison meteorite, also highlight (pre)biotic relevance different groups species. We report first evidence abundant heterocycles (with abundances relative methanol often order 10% error margin 30–50%) various representatives molecule classes, such carboxylic acids esters, aldehydes, ketones, alcohols. As pure hydrocarbons, some hydrogenated forms seem be dominant over their dehydrogenated counterparts. An interesting example tetrahydrofuran, it might more promising candidate searches ISM than long-sought furan. Our findings not only support guide future efforts investigate origins space, but they strongly encourage study, laboratory well modeling, topics ratios unbranched versus branched species astrophysical ice analogs.

Language: Английский

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