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| Titel |
Understanding Molecular Oxygen in Cometary Atmospheres |
| VerfasserIn |
Konstantinos S. Kalogerakis, Tom G. Slanger |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250140412
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| Publikation (Nr.) |
 EGU/EGU2017-3797.pdf |
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| Zusammenfassung |
| The Rosetta spacecraft discovered molecular oxygen during its orbiting of comet 67P
Churyumov-Gerasimenko [Bieler et al., Nature 526, 678-681 (2015)]. Based on previous
ground-based cometary observations, this was an unexpected finding, as was the
significant amount of O2 detected. The average value of [O2]/[H2O] reported by
Rosetta was 0.038, with a range of 0.01-0.10. Previous cometary ground-based
measurements have relied on optical measurements, whereas the Rosetta study utilized mass
spectroscopy.
We have initiated a research program to investigate optical spectra from various comets
for evidence of molecular oxygen. Such emission from comets has not been reported
previously, but there are compelling reasons for its presence in light of the Rosetta results. In
contrast to the situation with molecular oxygen, the presence of atomic oxygen in cometary
atmospheres is well established, with both O(1D) and O(1S) known emitters that give rise to
the green and red emission lines. Nevertheless, it it is generally assumed that their source is
photodissociation of CO2, H2O, and other oxygen-bearing species. Based on the most
recent results by the Rosetta mission, photodissociation of O2 itself becomes a
viable source of O(1D), which is produced over a large spectral region, 130-175
nm.
This type of information has profound consequences for the understanding of cometary
formation and the evolution of our solar system. This research also impacts future studies of
extrasolar planets. Optical techniques will be the only means for studying in situ exoplanet
atmospheres, at least in the short term, and thus it is critical to resolve the present
conundrum.
This material is based upon work supported by the U.S. National Science Foundation
under Award AST-1410297. |
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