Purple Photosynthesis on Planets Orbiting Red Dwarfs: Implications for Non-Green Biosignatures
To the point
Coelho and Kaltenegger suggest that on planets around cool red dwarfs purple bacteria could dominate photosynthesis, using infrared light and producing no oxygen, and they modeled how such worlds would look and what a detectable biosignature would be, while warning that non-biological explanations could mimic it.
