Scientists Discover Dying Sun-Like Stars Hold Molecule Vital for Creating Water

When you think of water, you wouldn't normally think of some of the hottest celestial bodies in the universe-stars.  But astronomers using ESA's Herschel space observatory are certainly making the connection after a recent study. They've found that a molecule vital for creating water exists in the burning embers of sun-like stars.

When stars like our own sun approach the ends of their lifetimes, they become dense, white dwarf stars. These stars cast off their outer layers of dust and gas into space, creating intricate patterns known as planetary nebulas. These nebulas enrich the local interstellar environment with elements that are then used to create the next generations of stars.

Planetary nebulas in particular contain a large proportion of the lighter "elements of life." These include carbon, nitrogen and oxygen, and are made by nuclear fusion in the parent star. When a star finally becomes a planetary nebula, intense radiation from a hot white dwarf may destroy molecules that had been previously ejected by the star and that are bound up in the clumps or rings of material seen in the periphery of planetary nebulas. This harsh radiation, in fact, was assumed to restrict the formation of new molecules.

Yet it turns out that this may not be the case. Using Herschel, astronomers have found that OH+, a molecule vital to the formation of water, seems to be present in this harsh environment.

"We think that a critical clue is the presence of the dense clumps of gas and dust, which are illuminated by UV and X-ray radiation emitted by the hot central star," said Isabel Aleman, one of the researchers, in a news release. "This high-energy radiation interacts with the clumps to trigger chemical reactions that lead to the formation of the molecules."

The findings reveal a bit more about the chemical reactions that occur in sun-like stars after they die. This, in turn, can tell us a bit about our own sun.

"Now we have even found that stars like our sun could contribute to the formation of water in the universe, even as they are in their death throes," said Goran Pibratt, one of the researchers, in a news release.

The findings are published in the journal Astronomy & Astrophysics.