Carbon monoxide detectors in our homeswarn of the dangerous accumulation of this odorless, colorless gas, which we usually associate with death. Astronomers, in fact, also believed that the accumulation of carbon monoxide in the atmosphere of the planet should be a sure sign of lifelessness. And here, a research team from the University of California at Riverside claims the opposite: celestial carbon monoxide detectors can actually warn us of the existence of simple life forms in a distant world.
Life and carbon monoxide: compatible or not?
"With the launch of the James Webb Space Telescopein two years, astronomers will be able to analyze the atmospheres of some solid exoplanets, ”says Edward Schwyterman, lead author and NASA research scientist at the University’s Earth Sciences Department. “It would be a shame to lose sight of the inhabited world only because we did not take into account all the possibilities.”
In a study that appeared today in TheAstrophysical Journal, the Schwyterman team used computer models of chemistry in the biosphere and the atmosphere to identify two intriguing scenarios in which carbon monoxide easily accumulates in planetary atmospheres with life.
In the first scenario, the team found the answers in deeppast of our planet. On the modern, oxygen-rich Earth, carbon monoxide cannot accumulate, because gas is quickly destroyed by chemical reactions in the atmosphere. But three billion years ago, the world was completely different. The oceans were already teeming with microbial life, but the atmosphere was almost deprived of oxygen, and the sun was much dimmer.
Team models show that the ancient versionThe inhabited Earth could maintain carbon monoxide levels of about 100 parts per million (ppm) - several orders of magnitude more than parts per billion that are in the atmosphere today.
"This means that we can expect highcarbon monoxide in an atmosphere of oxygen-rich exoplanets orbiting stars like our own sun, ”says Timothy Lyons, one of the co-authors of the study. "This is an excellent example of the ability to use the past of the Earth as a guide to finding life in other places in the Universe."
The second scenario is even more favorable forcarbon monoxide accumulations: photochemistry around red dwarf stars like Proxima Centauri, the closest star to our Sun at a distance of 4.2 light-years. Team models predict that if the planet around such a star is inhabited and rich in oxygen, we should expect the carbon monoxide content to be extremely high - from hundreds of parts per million to several percent.
"Given the different astrophysical contextsuch planets, we should not be surprised if we find microbial biospheres that contribute to the accumulation of high levels of carbon monoxide, ”says Schwyterman. "Nevertheless, they will certainly not be the best place for the life of people or animals who walk the Earth."
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