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Noble Gas Abundance Ratios Indicate the Agglomeration of 67P/Churyumov-Gerasimenko from Warmed-up Ice

Mousis, O. ; Ronnet, T. LU ; Lunine, J. I. ; Luspay-Kuti, A. ; Mandt, K. E. ; Danger, G. ; Pauzat, F. ; Ellinger, Y. ; Wurz, P. and Vernazza, P. , et al. (2018) In Astrophysical Journal Letters 865(1).
Abstract

The origin of cometary volatiles remains a major open question in planetary science. Comets may have either agglomerated from crystalline ices condensed in the protosolar nebula (PSN) or from amorphous ice originating from the molecular cloud and interstellar medium. Here, based on the recent argon, krypton, and xenon measurements performed by the ROSINA mass spectrometer on board the European Space Agency's Rosetta spacecraft in the coma of 67P/Churyumov-Gerasimenko, we show that these noble gas relative abundances can be explained if the comet's building blocks formed from a mixture of gas and H2O grains resulting from the annealing of pristine amorphous ice (i.e., originating from the presolar cloud) in the PSN. In this... (More)

The origin of cometary volatiles remains a major open question in planetary science. Comets may have either agglomerated from crystalline ices condensed in the protosolar nebula (PSN) or from amorphous ice originating from the molecular cloud and interstellar medium. Here, based on the recent argon, krypton, and xenon measurements performed by the ROSINA mass spectrometer on board the European Space Agency's Rosetta spacecraft in the coma of 67P/Churyumov-Gerasimenko, we show that these noble gas relative abundances can be explained if the comet's building blocks formed from a mixture of gas and H2O grains resulting from the annealing of pristine amorphous ice (i.e., originating from the presolar cloud) in the PSN. In this scenario, the different volatiles released during the amorphous-to-crystalline ice phase transition would have been subsequently trapped at lower temperatures in stoichiometric hydrate or clathrate hydrate forms by the crystalline water ice generated by the transition. Once crystalline water was completely consumed by clathration in the ∼25-80 K temperature range, the volatile species remaining in the gas phase would have formed pure condensates at lower temperatures. The formation of clathrates hydrates and pure condensates to explain the noble gas relative abundances is consistent with a proposed interstellar origin of molecular oxygen detected in 67P/Churyumov-Gerasimenko, and with the measured molecular nitrogen depletion in comets.

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published
subject
keywords
astrobiology, comets: general, comets: individual (67P/Churyumov-Gerasimenko), methods: numerical, solid state: volatile
in
Astrophysical Journal Letters
volume
865
issue
1
article number
L11
publisher
University of Chicago Press
external identifiers
  • scopus:85053860292
ISSN
2041-8205
DOI
10.3847/2041-8213/aadf89
language
English
LU publication?
no
id
cda7d053-bafb-413c-a2b2-4bd12a2af248
date added to LUP
2019-05-29 09:23:08
date last changed
2019-11-20 05:45:59
@article{cda7d053-bafb-413c-a2b2-4bd12a2af248,
  abstract     = {<p>The origin of cometary volatiles remains a major open question in planetary science. Comets may have either agglomerated from crystalline ices condensed in the protosolar nebula (PSN) or from amorphous ice originating from the molecular cloud and interstellar medium. Here, based on the recent argon, krypton, and xenon measurements performed by the ROSINA mass spectrometer on board the European Space Agency's Rosetta spacecraft in the coma of 67P/Churyumov-Gerasimenko, we show that these noble gas relative abundances can be explained if the comet's building blocks formed from a mixture of gas and H<sub>2</sub>O grains resulting from the annealing of pristine amorphous ice (i.e., originating from the presolar cloud) in the PSN. In this scenario, the different volatiles released during the amorphous-to-crystalline ice phase transition would have been subsequently trapped at lower temperatures in stoichiometric hydrate or clathrate hydrate forms by the crystalline water ice generated by the transition. Once crystalline water was completely consumed by clathration in the ∼25-80 K temperature range, the volatile species remaining in the gas phase would have formed pure condensates at lower temperatures. The formation of clathrates hydrates and pure condensates to explain the noble gas relative abundances is consistent with a proposed interstellar origin of molecular oxygen detected in 67P/Churyumov-Gerasimenko, and with the measured molecular nitrogen depletion in comets.</p>},
  author       = {Mousis, O. and Ronnet, T. and Lunine, J. I. and Luspay-Kuti, A. and Mandt, K. E. and Danger, G. and Pauzat, F. and Ellinger, Y. and Wurz, P. and Vernazza, P. and Sergeant D'Hendecourt, L. Le},
  issn         = {2041-8205},
  language     = {eng},
  month        = {09},
  number       = {1},
  publisher    = {University of Chicago Press},
  series       = {Astrophysical Journal Letters},
  title        = {Noble Gas Abundance Ratios Indicate the Agglomeration of 67P/Churyumov-Gerasimenko from Warmed-up Ice},
  url          = {http://dx.doi.org/10.3847/2041-8213/aadf89},
  doi          = {10.3847/2041-8213/aadf89},
  volume       = {865},
  year         = {2018},
}