New space evidence suggests our water could be older than the sun

Astronomers say the water that fills Earth's oceans — and the stuff you use to brew your morning cup of coffee or tea — may be older than the sun itself. 

A team of researchers used a giant Chilean telescope, the Atacama Large Millimeter Array, to make an unprecedented detection of a rare form of so-called "heavy water" in a young star system about 1,300 light-years away in space. It is the first direct evidence of water remaining intact through an interstellar journey, from molecular clouds to the materials that form planets.

The system, V883 Orionis, revealed that the water in its surrounding planet-forming disk dates back long before the star, surviving the violence of the star's own birth. 

This discovery suggests that much of the water in our own solar system could have come from billions-of-years-old ices, the researchers said. 

"Our detection indisputably demonstrates that the water seen in this planet-forming disk must be older than the central star and formed at the earliest stages of star and planet formation," said Margot Leemker, lead author of the research at the University of Milan, in a statement. "This presents a major breakthrough in understanding … how this water made its way to our solar system, and possibly Earth, through similar processes."

If water is hardy enough to survive every stage of star and planet development, then the ingredients for life aren't just created by stars but can be inherited from the cold stretches of space between them. The implications could connect water — and, by extension, the potential for life — across the cosmos. The new study appears in the journal Nature Astronomy. 

The key to the team's findings rests on the detection of a rare form of "heavy water," known as doubly deuterated water, which contains two atoms of deuterium, a heavier version of hydrogen. Scientists measured how much of the molecule exists in V883 Orionis' disk compared to normal water and singly deuterated water. If the water were destroyed and later reformed in the disk, its doubly deuterated water levels would be low, according to the study. 

But the disk contains a high amount of it, similar to the levels seen in extremely young developing stars and even in comets from our own solar system. That's a compelling sign that the ice in this disk is inherited rather than new.

In other words, the same molecules of water that froze onto dust in an ancient interstellar cloud are still present in the disk that will one day form planets. The researchers believe this could link the chemistry of distant deep space to the familiar water on Earth, perhaps through icy bodies delivering water to planets.

While some scientists believe primitive Earth vented gases 4.5 billion years ago that eventually created an atmosphere allowing rain to fall and pool into oceans, many think the large bodies of water formed because comets and icy rocks brought water to it through collisions — or some combination of the two.

"Until now, we weren’t sure if most of the water in comets and planets formed fresh in young disks like V883 Ori, or [originated] from ancient interstellar clouds," said John Tobin, a co-author from the National Science Foundation, in a statement. 

The study may also help explain how origins-of-life ingredients behave in these environments. In the V883 Orionis disk, those chemicals seem like they've been tainted by heat or radiation. The water, on the other hand, appears pristine. This contrast might shed light on why water is such a good carrier of life's raw materials, remaining stable, even in hostile conditions that would destroy other molecules.