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The search for extraterrestrial life has fascinated mankind for generations, with all sorts of theories about its possible existence, if any. For all those hoping to see an abundance of E.T., a new study puts a bit of a brake on its location.
A study entitled "A Limited Living Area for a Complex Life" published in The Astrophysical Journal dramatically reduces the number of planets that can potentially support intelligent living. The definition of the "habitable zone" – the distance between a planet and a star – "is probably limited compared to that of the microbial life" and the parameters of the complex life are much more strict.
"Imagine a" livable zone for complex living "defined as a safe zone where it would be plausible to preserve ecosystems as rich as those we find on Earth today," said Timothy Lyons, professor at the University of California. 39, University of California Riverside in a statement. "Our results indicate that complex ecosystems like ours can not exist in most areas of the livelihood zone as traditionally defined."
Additional parameters necessary for the existence of a complex life-based carbon, such as the elimination of toxic gases (carbon dioxide and carbon monoxide) significantly limit the number of exoplanets Potential for life, added Mr. Lyons.
To make their decision, the researchers created a model that examines the atmospheric climate and photochemistry to establish estimated levels of carbon dioxide, a lethal gas, though necessary to warm the planet. In turn, they found that the tolerance for carbon dioxide levels of 0.01, 0.1 and 1 bar reduced the percentage of "habitable zone for complex life" to 21%, 32% and 50%, respectively.
"To maintain liquid water at the edge of the conventional habitable zone, a planet would need tens of thousands of times more carbon dioxide than Earth has today," said Edward Schwieterman, principal author of the 'study. "This far exceeds the known levels of toxicity to human and animal life on Earth."
The study puts additional strain on the possibility of a complex extraterrestrial life in our neighborhood, noting that stars such as Proxima Centauri and TRAPPIST-1 exhibit the type and levels of ultraviolet radiation that "can lead to high concentrations of carbon monoxide, another deadly gas ". . "
In March, a separate study was published that suggests that the presence of carbon monoxide could be a promising "biosignature" for extraterrestrial life and scientists should consider this, despite the potential for harm.
The list of exoplanets is close to 4,000 at this stage, including the recently discovered Wolf 503b, located 145 light-years from Earth. The new parameters have greatly enriched this list and could help researchers focus their efforts on the criteria defined in the study.
"Our discoveries provide a way to decide which of these myriad planets we need to observe in more detail," said co-investigator Christopher Reinhard in the statement. "We could identify otherwise habitable planets with levels of carbon dioxide or carbon monoxide that are probably too high to support a complex life."
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