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Scientists have found that molecular oxygen around the comet 67P is not produced on its surface, as some have suggested, but may come from its body.
The Rosetta spacecraft of the European Space Agency escorted comet 67P / Churyumov-Gerasimenko on her journey around the sun from August 2014 to September 2016, dropping a probe and ending with s & # 39; Crushing on its surface
sun ice on its "sublime" surface – transforms from solid to gas forming a gas atmosphere called coma. The badysis of coma by instruments on Rosetta revealed that it contained not only water, carbon monoxide and carbon dioxide, but also molecular oxygen.
Molecular oxygen is two joined oxygen atoms. , where it is produced by photosynthesis. It has been detected previously around some of Jupiter's icy moons, but it was not expected to be around a comet.
The Rosetta science team initially reported that oxygen probably came from the main nucleus of the comet. This meant that it was "primordial" – that it was already present when the comet itself formed at the beginning of the Solar System 4.6 billion years ago.
A group of external researchers however suggested that there could be a different source of molecular oxygen. comets. They had discovered a new way of producing molecular oxygen in space, triggered by energetic ions – electrically charged molecules. They proposed that reactions with energetic ions on the surface of comet 67P could be the source of molecular oxygen detected
![Molecular oxygen in the atmosphere of the comet not created on its surface [19659010] Views of the comet Rosetta. Credit: ESA
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<p> Now, members of the Rosetta team have badyzed the oxygen data of 67P in the light of the new theory. In an article published today in <i> Nature Communications </i> and led by physicists from Imperial College London, they report that the proposed mechanism for producing oxygen at the surface comet's is not enough to explain the levels seen in coma. 19659012] The lead author, Mr. Kevin Heritier, of the Department of Physics, Imperial, said: "The first detection of molecular oxygen in 67P coma was both very surprising and exciting. " </p>
<p> "We tested the new theory We found that the amount of energy ions present could not produce enough molecular oxygen to account for the amount of molecular oxygen observed in the coma. 19659005] Co-author Dr. Marina Galand, of the Department of Physics at the Imperial and co-research scientist of the Rosetta Plasma Consortium, added: "Molecular oxygen surface generation can still happen on 67P, but the majority of molecular oxygen in coma is not produced by such a process. "</p>
<p> The new badysis is consistent with the original finding of the team, that oxygen Molecular is probably essential. Other theories have been proposed and can not yet be ruled out, but the primordial theory currently best fits the data </p>
<p> This is also supported by recent theories that revisit the formation of molecular oxygen in Dark clouds and the presence of molecular oxygen in the early solar system. In this model, the molecular oxygen created frozen on small grains of dust. These grains collected more matter, eventually accumulating the comet and blocking oxygen in the nucleus.
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