M dwarf UV radiation skews exoplanet biosignatures, study finds

A study submitted to arXiv on Aug. 19 found that ignoring a host star's ultraviolet output can mislead biosignature readings on exoplanets. Simulated planets around 5-billion-year-old M dwarfs built up to 10 times more methane, while UV from young stars created ozone without life — up to 100,000 times more.

• Old M dwarfs: up to 10x more methane, 68% stronger signal
• UV from young stars makes ozone without life, up to 100,000x
• Simulated planets orbited stars aged 650 million to 5 billion years
• Biosignatures can't be read without the star's UV environment