Sulphur-bearing species in the coma of comet 67P/Churyumov–Gerasimenko

Calmonte, Ursina; Altwegg, Kathrin; Balsiger, H.; Berthelier, Jean‐Jacques; Bieler, André; Cessateur, Gaël; Dhooghe, Frederik; Dishoeck, E. F. van; Fiethe, Björn; Fuselier, S. A.; Gombosi, T. I.; Hässig, Myrtha; Roy, Léna Le; Rubin, Martin; Sémon, Thierry; Tzou, Chia-Yu; Wampfler, S. F.

doi:10.1093/mnras/stw2601

Cited by 180 publications

(329 citation statements)

References 95 publications

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“…Only a small amount of hydrated sulfur-bearing species is predicted to be present on Io's surface, if any. -The inventory of sulfur-bearing molecules recently implemented by the Rosetta finding (Calmonte et al 2016) supports evidence for the occurrence of radiolysis. If so, that inventory would be even more implemented including the species discussed here.…”

Section: Resultsmentioning

confidence: 67%

Thermal and energetic processing of astrophysical ice analogues rich in SO₂

Kaňuchová

Boduch

Domaracka

et al. 2017

A&A

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Context. Sulfur is an abundant element in the cosmos and it is thus an important contributor to astrochemistry in the interstellar medium and in the solar system. Astronomical observations of the gas and of the solid phases in the dense interstellar/circumstellar regions have evidenced that sulfur is underabundant. The hypothesis to explain such a circumstance is that it is incorporated in some species in the solid phase (i.e. as frozen gases and/or refractory solids) and/or in the gas phase, which for different reasons have not been observed so far. Aims. Here we wish to give a contribution to the field by studying the chemistry induced by thermal and energetic processing of frozen mixtures of sulfur dioxide (one of the most abundant sulfur-bearing molecules observed so far) and water. Methods. We present the results of a series of laboratory experiments concerning thermal processing of different H 2 O:SO 2 mixtures and ion bombardment (30 keV He + ) of the same mixtures. We used in situ Fourier transform infrared (FTIR) spectroscopy to investigate the induced effects. Results. The results indicate that ionic species such as HSO − 3 , HSO − 4 , and S 2 O 2− 5 are easily produced. Energetic processing also produces SO 3 polymers and a sulfurous refractory residue. Conclusions. The produced ionic species exhibit spectral features in a region that, in astronomical spectra of dense molecular clouds, is dominated by strong silicate absorption. However, such a dominant feature is associated with some spectral features, some of which have not yet been identified. We suggest adding the sulfur-bearing ionic species to the list of candidates to help explain some of those features. In addition, we suggest that once expelled in the gas phase by sublimation, due to the temperature increase, and/or by non-thermal erosion those species would constitute a class of molecular ions not detected so far. We also suggest that molecular sulfur-bearing ions could be present on the surfaces and/or in the atmospheres of several objects in the solar system, for example icy satellites of the giant planets and comets.

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Section: Resultsmentioning

confidence: 67%

Thermal and energetic processing of astrophysical ice analogues rich in SO₂

Kaňuchová

Boduch

Domaracka

et al. 2017

A&A

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“…The instrument sensitivities for HF, F, HCl, Cl, HBr and Br have been calculated using literature data on electron ionization cross-sections for these compounds from Vinodkumar et al (2010), together with the known mass/charge dependent transmission and detection efficiencies for the fragmentation products in DFMS. The following sensitivity values were used: S F-F = 9.75 × 10 −20 cm 3 , S HF-HF = S HF-F = 1.63 × 10 −19 cm 3 , S Cl-Cl = 2.45 × 10 −19 cm 3 , S HCl-HCl = S HCl-Cl = 2.58 × 10 −19 cm 3 , S Br-Br = 5.66 × 10 −19 cm 3 and S HBr-HBr = S HBr-Br = 5.76 × 10 −19 cm 3 ; these numbers are believed to be precise within a factor of 2 (Calmonte et al 2016). The same values have been used for all corresponding isotopes.…”

Section: Neutral Abundancesmentioning

confidence: 85%

“…If the hydrogen halides indeed are the major halogen-bearing species, the ratios given above are good proxies for the halogen-to-oxygen ratios. The ratios given above are subject to a systematic error that stems largely from the uncertainties on the sensitivities, believed to be within a factor of 2 (Calmonte et al 2016). …”

Section: Halogen To Oxygen Ratiosmentioning

confidence: 99%

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Halogens as tracers of protosolar nebula material in comet 67P/Churyumov–Gerasimenko

Dhooghe

Keyser

Altwegg

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We report the first in situ detection of halogens in a cometary coma, that of 67P/ChuryumovGerasimenko. Neutral gas mass spectra collected by the European Space Agency's Rosetta spacecraft during four periods of interest from the first comet encounter up to perihelion indicate that the main halogen-bearing compounds are HF, HCl and HBr. The bulk elemental abundances relative to oxygen are ∼8.9 × 10 −5 for F/O, ∼1.2 × 10 −4 for Cl/O and ∼2.5 × 10for Br/O, for the volatile fraction of the comet. The cometary isotopic ratios for 37 Cl/ 35 Cl and 81 Br/ 79 Br match the Solar system values within the error margins. The observations point to an origin of the hydrogen halides in molecular cloud chemistry, with frozen hydrogen halides on dust grains, and a subsequent incorporation into comets as the cloud condensed and the Solar system formed.

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“…CO Fourth Positive and Cameron bands are present but atomic emissions, other than those produced by resonance scattering, particularly O I λ1304 and three S I multiplets identified in the figure, are significantly weaker. The atomic sulfur emissions are resonantly scattered radiation from the dissociation products of the many sulfurcontaining molecules identified by ROSINA (Calmonte et al 2016), and will be discussed in a separate paper. Like the S I multiplets, both O I λ1304 and Lyman-β show emission from resonance scattering on the anti-sunward side of the nucleus from the extended coma, whose presence complicates the extraction of the electron excited emissions on the sunward side.…”

Section: Limb Observations Around Perihelionmentioning

confidence: 99%

FUV Spectral Signatures of Molecules and the Evolution of the Gaseous Coma of Comet 67P/Churyumov–Gerasimenko

Feldman

A’Hearn

Bertaux

et al. 2017

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The Alice far-ultraviolet imaging spectrograph onboard Rosetta observed emissions from atomic and molecular species from within the coma of comet 67P/Churyumov-Gerasimenko during the entire escort phase of the mission from 2014 August to 2016 September. The initial observations showed that emissions of atomic hydrogen and oxygen close to the surface were produced by energetic electron impact dissociation of H 2 O. Following delivery of the lander, Philae, on 2014 November 12, the trajectory of Rosetta shifted to near-terminator orbits that allowed for these emissions to be observed against the shadowed nucleus that, together with the compositional heterogeneity, enabled us to identify unique spectral signatures of dissociative electron impact excitation of H 2 O, CO 2 , and O 2 . CO emissions were found to be due to both electron and photoexcitation processes. Thus we are able, from far-ultraviolet spectroscopy, to qualitatively study the evolution of the primary molecular constituents of the gaseous coma from start to finish of the escort phase. Our results show asymmetric outgassing of H 2 O and CO 2 about perihelion, H 2 O dominant before and CO 2 dominant after, consistent with the results from both the in situ and other remote sensing instruments on Rosetta.

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Sulphur-bearing species in the coma of comet 67P/Churyumov–Gerasimenko

Cited by 180 publications

References 95 publications

Thermal and energetic processing of astrophysical ice analogues rich in SO₂

Thermal and energetic processing of astrophysical ice analogues rich in SO₂

Halogens as tracers of protosolar nebula material in comet 67P/Churyumov–Gerasimenko

FUV Spectral Signatures of Molecules and the Evolution of the Gaseous Coma of Comet 67P/Churyumov–Gerasimenko

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Sulphur-bearing species in the coma of comet 67P/Churyumov–Gerasimenko

Cited by 180 publications

References 95 publications

Thermal and energetic processing of astrophysical ice analogues rich in SO2

Thermal and energetic processing of astrophysical ice analogues rich in SO2

Halogens as tracers of protosolar nebula material in comet 67P/Churyumov–Gerasimenko

FUV Spectral Signatures of Molecules and the Evolution of the Gaseous Coma of Comet 67P/Churyumov–Gerasimenko

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Thermal and energetic processing of astrophysical ice analogues rich in SO₂

Thermal and energetic processing of astrophysical ice analogues rich in SO₂