A group of researchers recently found that buildup of toxic gases in the atmosphere in different planets make them unfit for life. If accurate, this latest discovery will reduce the number of planets outside solar system suitable for supporting life.
In order to find the number of exoplanets which can sustain life, scientists studied climate and photochemistry of different planets by looking at simulations during the course of the research. The group soon discovered that simple animal life can only exist in exoplanets which are located more than half of the traditional habitable zone of a star system. However, towards the edge of the habitable zone, a planet would need to have extremely high amount of carbon dioxide for the planet to sustain liquid water.
Talking about the latest findings, Edward Schwieterman, a NASA Postdoctoral Program fellow and the lead author of the study, said, “To sustain liquid water at the outer edge of the conventional habitable zone, a planet would need tens of thousands of times more carbon dioxide than Earth has today. That’s far beyond the levels known to be toxic to human and animal life on Earth”.
After their discovery, the group found that in some cases, there is no habitable zone. For example, cooler stars emit intense ultraviolet radiation which might result in high carbon monoxide concentration in a planet’s atmosphere. Needless to say, higher life forms cannot survive in such environments.
As a result, the researchers think that the number of habitable planets in the universe might be lower than we previously thought. The group expects that the findings from the research will help astronomers to narrow down search for alien life form significantly.
The paper was published in The Astrophysical Journal earlier on June 10.