Infrared detection of aliphatic organics on a cometary nucleus

Raponi, A.; Ciarniello, M.; Capaccioni, F.; Mennella, V.; Filacchione, G.; Vinogradoff, Vassilissa; Poch, Olivier; Beck, Pierre; Quirico, E.; Sanctis, M. C. De; Moroz, L. V.; Kappel, David; Erard, S.; Bockelée‐Morvan, Dominique; Longobardo, A.; Tosi, F.; Palomba, E.; Combe, Jean-Philippe; Rousseau, Batiste; Arnold, G.; Carlson, R. W.; Pommerol, Antoine; Pilorget, C.; Fornasier, S.; Bellucci, G.; Barucci, A.; Mancarella, F.; Formisano, M.; Rinaldi, G.; Istiqomah, I.; Leyrat, C.

doi:10.1038/s41550-019-0992-8

Cited by 52 publications

(60 citation statements)

References 52 publications

(63 reference statements)

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“…a Average reflectance spectrum of the surface of comet 67P obtained from our VIRTIS-M data. The absorption features observed at 3.38, 3.42 and 3.47 µm in this spectrum are attributed to C−H stretching from organic matter (10). b Average reflectance spectrum of the surface of comet 67P obtained from VIRTIS-M data (previous calibration) (5) c Transmittance spectrum of NH4 + HCOOat 298 K (83) d Transmittance spectrum of (NH4 + )2 SO4 2at ambient temperature and pressure conditions (84) e Transmittance spectra of (NH4 + )2 SO4 2from 288 to 183 K in (85).…”

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confidence: 75%

“…1, 2, S5, S6 and S7 was obtained from a recalibration of data acquired by the VIRTIS-M (Visual Infrared and Thermal Imaging Spectrometer -Mapper) Infrared (IR) channel (2), reducing instrumental artifacts and improving the radiometric accuracy. We summarize the data reduction below; full details have been published elsewhere (10).…”

Section: Reflectance Spectrum Of the Average Surface Of Comet 67pmentioning

confidence: 99%

“…The estimated signal-to-noise ratio is ~70 for the absorption feature at 3.1 µm, ~20 for the feature at 3.3 µm, and ~7 for the feature at 3.4 µm. The spectral ratio between 3.35-3.60 µm indicates the presence of the C−H stretching modes in carbonaceous compounds (10). Ammonium salts also exhibit a weaker reflectance minimum centered around 3.50 µm whose identification on the spectrum of comet 67P is impeded by its proximity with the C−H stretching modes and the limited spectral resolution and sampling (respectively of Δλresolution = 0.039 µm and Δλsampling = 0.020 µm for the laboratory spectrum and of Δλresolution = 0.015 µm and Δλsampling = 0.020 µm for the VIRTIS spectrum after removal of the even bands, as explained above).…”

Section: Fig S5 Comparison Of Nh4 + Hcoospectrum With the Average Smentioning

confidence: 99%

“…Ammonium chloride appears as a less likely contributor. The absorptions at 3.38, 3.42 and 3.47 µm in the comet spectrum are attributed to C−H stretching vibrations of organic compounds (10). The identification on the spectrum of comet 67P of a weaker N−H mode of ammonium salts centered around 3.50 µm is impeded by the proximity of the C−H stretching modes and the limited spectral resolution and sampling (respectively of 0.039 µm and 0.020 µm for the laboratory spectrum and of 0.015 µm and 0.020 µm for the VIRTIS spectrum).…”

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confidence: 99%

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Ammonium salts are a reservoir of nitrogen on a cometary nucleus and possibly on some asteroids

Poch

Istiqomah

Quirico

et al. 2020

Science

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The measured nitrogen-to-carbon ratio in comets is lower than for the Sun, a discrepancy which could be alleviated if there is an unknown reservoir of nitrogen in comets. The nucleus of comet 67P/Churyumov-Gerasimenko exhibits an unidentified broad spectral 2 reflectance feature around 3.2 µm, which is ubiquitous across its surface. Based on laboratory experiments, we attribute this absorption band to ammonium salts mixed with dust on the surface. The depth of the band indicates that semi-volatile ammonium salts are a substantial reservoir of nitrogen in the comet, potentially dominating over refractory organic matter and more volatile species. Similar absorption features appear in the spectra of some asteroids, implying a compositional link between asteroids, comets and the parent interstellar cloud.

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confidence: 75%

Section: Reflectance Spectrum Of the Average Surface Of Comet 67pmentioning

confidence: 99%

Section: Fig S5 Comparison Of Nh4 + Hcoospectrum With the Average Smentioning

confidence: 99%

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confidence: 99%

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Ammonium salts are a reservoir of nitrogen on a cometary nucleus and possibly on some asteroids

Poch

Istiqomah

Quirico

et al. 2020

Science

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“…geomorphological regions on the nucleus surface by observing the Northern hemisphere before perihelion (El-Maarry et al 2015) and the Southern hemisphere in the post-perihelion stage (El-Maarry et al 2016). The composition of the nucleus surface, as inferred by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) imaging spectrometer (Coradini et al 2007), is a mixture of opaque minerals, organics (Capaccioni et al 2015;Raponi et al 2020), ammonium salts (Poch et al 2020), and water ice (Barucci et al 2016;Filacchione et al 2016;Raponi et al 2016). The amount of water ice on the surface has a diurnal and seasonal variation (De Sanctis et al 2015;Ciarniello et al 2016).…”

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confidence: 99%

67P/Churyumov–Gerasimenko’s dust activity from pre- to post-perihelion as detected by Rosetta/GIADA

Longobardo

Corte

Rotundi

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We characterized the 67P/Churyumov–Gerasimenko’s dust activity, by analysing individual dust particle velocity and momentum measurements of Grain Impact Analyser and Dust Accumulator (GIADA), the dust detector onboard the ESA/Rosetta spacecraft, collecting dust from tens to hundreds of kilometres from the nucleus. Specifically, we developed a procedure to trace back the motion of dust particles down to the nucleus, identifying the surface’s region ejecting each dust particle. This procedure has been developed and validated for the first part of the mission by Longobardo et al. and was extended to the entire GIADA data set in this work. The results based on this technique allowed us to investigate the link between the dust porosity (fluffy/compact) and the morphology of the ejecting surface (rough/smooth). We found that fluffy and compact particles, despite the lack of correlation in their coma spatial distribution (at large nucleocentric distances) induced by their different velocities, have common ejection regions. In particular, the correlation between the distributions of fluffy and compact particles is maintained up to an altitude of about 10 km. Fluffy particles are more abundant in rough terrains. This could be the result of past cometary activity that resurfaced the smooth terrains and/or of the comet formation process that stored the fluffy particles inside the voids between the pebbles. The variation of fluffy particle concentration between rough and smooth terrains agrees with predictions of comet formation models. Finally, no correlation between dust distribution on the nucleus and surface thermal properties was found.

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Identification of Ammonium Salts on Comet 67P/C-G Surface from Infrared VIRTIS/Rosetta Data Based on Laboratory Experiments. Implications and Perspectives

Poch,

Istiqomah,

Quirico

et al. 2023

Astrophysics and Space Science Proceedings

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The nucleus of comet 67P/Churyumov-Gerasimenko exhibits a broad spectral reflectance feature around 3.2 µm, which is omnipresent in all spectra of the surface, and whose attribution has remained elusive since its discovery. Based on laboratory experiments, we have shown that most of this absorption feature is due to ammonium (NH4 + ) salts mixed with the dark surface material. The depth of the band is compatible with semi-volatile ammonium salts being a major reservoir of nitrogen in the comet, which could dominate over refractory organic matter and volatile species. These salts may thus represent the longsought reservoir of nitrogen in comets, possibly bringing their nitrogen-tocarbon ratio in agreement with the solar value. Moreover, the reflectance spectra of several asteroids are compatible with the presence of NH4 + salts at their surfaces. The presence of such salts, and other NH4 + -bearing compounds on as-teroids, comets, and possibly in proto-stellar environments, suggests that NH4 + may be a tracer of the incorporation and transformation of nitrogen in ices, minerals and organics, at different phases of the formation of the Solar System.

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Infrared detection of aliphatic organics on a cometary nucleus

Cited by 52 publications

References 52 publications

Ammonium salts are a reservoir of nitrogen on a cometary nucleus and possibly on some asteroids

Ammonium salts are a reservoir of nitrogen on a cometary nucleus and possibly on some asteroids

67P/Churyumov–Gerasimenko’s dust activity from pre- to post-perihelion as detected by Rosetta/GIADA

Identification of Ammonium Salts on Comet 67P/C-G Surface from Infrared VIRTIS/Rosetta Data Based on Laboratory Experiments. Implications and Perspectives

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