Let's say you're a planetary scientist searching for signs of life on other worlds, and you happen upon an exoplanet whose atmosphere contains a large proportion of oxygen. Jackpot, right? Not exactly. New research shows planets orbiting red dwarf stars may harbor signatures of life (like oxygen) that are actually generated by non-biological processes.
New research led by Tsinghua University astronomer Feng Tian has shown that M dwarf, aka "red dwarf" stars – which are estimated to account for a whopping three-quarters of the stars in the Milky Way – are conducive to chemical reactions on their orbiting worlds that could suggest the presence of life where none actually exists.
Astronomers found that M dwarf stars have relatively high levels of far-ultraviolet radiation — 1,000 times more than the sun. These emissions could trigger chemical reactions in an orbiting planet's atmosphere that create oxygen and ozone.
"This could be taken as a false positive (for life)," said [Tian].
"If you observe these planets’ atmospheres, you’ll see oxygen and you may think ‘Oh the oxygen could come from life, like plants on our own planet,’ but actually that is not the case," Tian told reporters during a webcast press conference at the American Astronomical Society meeting in Denver this week.
An important reminder that oxygen – like methane – is far from a surefire sign of life. That's not necessarily a compelling reason to forego searching for life around red dwarfs – but it is, perhaps, a reminder that life is theorized to exist in plenty of other places, as well.