Red Dwarfs are Too Dim to Generate Complex Life
upstart writes:
Red Dwarfs Are Too Dim To Generate Complex Life:
One of the most consequential events-maybe the most consequential one throughout all of Earth's long, 4.5 billion year history-was the Great Oxygenation Event (GOE). When photosynthetic cyanobacteria arose on Earth, they released oxygen as a metabolic byproduct. During the GOE, which began around 2.3 billion years ago, free oxygen began to slowly accumulate in the atmosphere.
It took about 2.5 billion years for enough oxygen to accumulate in the atmosphere for complex life to arise. Complex life has higher energy needs, and aerobic respiration using oxygen provided it. Free oxygen in the atmosphere eventually triggered the Cambrian Explosion, the event responsible for the complex animal life we see around us today.
[...] The question is, do red dwarfs emit enough radiation to power photosynthesis that can trigger a GOE on planets orbiting them?
New research tackles this question. It's titled "Dearth of Photosynthetically Active Radiation Suggests No Complex Life on Late M-Star Exoplanets," and has been submitted to the journal Astrobiology. The authors are Joseph Soliz and William Welsh from the Department of Astronomy at San Diego State University. Welsh also presented the research at the 247th Meeting of the American Astronomical Society, and the paper is currently available at arxiv.org.
"The rise of oxygen in the Earth's atmosphere during the Great Oxidation Event (GOE) occurred about 2.3 billion years ago," the authors write. "There is considerably greater uncertainty for the origin of oxygenic photosynthesis, but it likely occurred significantly earlier, perhaps by 700 million years." That timeline is for a planet receiving energy from a Sun-like star.
[...] 63 billion years is far longer than the current age of the Universe, so the conclusion is clear. There simply hasn't been enough time for oxygen to accumulate on any red dwarf planet and trigger the rise of complex life, like happened on Earth with the GOE.
See also:
- Dearth of Photosynthetically Active Radiation Suggests No Complex Life on Late M-Star Exoplanets
- Complex Life Around Most Milky Way Stars May Be Impossible
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