Life on alien planets hampered by the ‘wrong kind of supernova’

ALIEN life may be more unlikely than commonly thought, according to a British study that hints at a cosmic lack of phosphorus, which is vital to energy storage and transfer in cells, and part of the chemical backbone of DNA.

Phosphorus is created in supernovae, the explosions of massive stars at the end of their lives. But the research suggests that typical supernovae may not provide the conditions needed for forging the element. Earth may have been unusually lucky, because it happened to be situated close enough to the “right” kind of supernova.

Dr Jane Greaves, an astronomer from the University of Cardiff, said: “The route to carrying phosphorus into newborn planets looks rather precarious. We already think that only a few phosphorus-bearing minerals that came to the Earth, probably in meteorites, were reactive enough to get involved in making proto-biomolecules.

“If phosphorus is sourced from supernovae, and then travels across space in meteoritic rocks, I’m wondering if a young planet could find itself lacking in reactive phosphorus because of where it was born? That is, it started off near the wrong kind of supernova?

“In that case, life might really struggle to get started out of phosphorus-poor chemistry, on another world otherwise similar to our own.”

The evidence comes from observations of two supernova “remnants”, Cassiopeia A (Cas A) and the famous Crab Nebula. The team looked for signatures of phosphorus and iron from the Crab Nebula, the aftermath of a supernova 6,500 light years away in the constellation of Taurus. A previous study had searched for phosphorus from Cas A, 11,000 light years away.

Comparing results from the two observations showed much less phosphorus from the Crab Nebula than Cas A, which came as a surprise to the scientists.

Dr Phil Cigan, another Cardiff astronomer, said: “The two explosions seem to differ from each other, perhaps because Cas A results from the explosion of a rare super-massive star.”

The findings were presented at the European Week of Astronomy and Space Science meeting in Liverpool.