Scientists discover biosignature molecule in failed star-Here is what it means for extraterrestrial life

Illustration of a brown dwarf, showcasing its dense, dimly glowing substellar atmosphere. (Image: NOIRLab/NSF/AURA/R. Proctor)

Astrophysicists have found phosphine (PH₃) in the atmosphere of a brown dwarf star, Wolf 1130C, located 54 light-years away from Earth. This is the first confirmed detection of phosphine across all brown dwarfs.

This raises questions about phosphorus chemistry in substellar environments. Brown dwarfs or “failed stars," are too small to sustain hydrogen fusion and are especially interesting for chemical studies.

Phosphine is associated with biological processes on Earth. It is one of many biosignatures for extraterrestrial life. However, PH₃ can form through non-biological processes, including on the atmospheres of Jupiter and Saturn.

This makes its biological interpretation more difficult. The detection of phosphine in Wolf 1130C provokes further questions about the chemistry of phosphorus in extreme environments.

Wolf 1130C is an ancient object that is over 10 billion years old. The abundance of phosphine aligns with some theoretical atmospheric models, yet the absence of phosphine in other brown dwarf and exoplanets shows phosphorus chemistry is likely different for each source.

Scientists emphasise that continued research into the formation of phosphine in such atmospheres is crucial for accurately and cautiously interpreting potential biosignatures in the search for extraterrestrial life.