Water in our solar system likely formed billions of years before the sun

The mystery of where water first came from has puzzled scientists for decades.

But after “tracking H20 across the galaxy” to a star 1,300 light-years away, they may finally have an answer.

New research has not only uncovered the possible ‘missing link’ for how water reached Earth, but also suggests that H20 in our solar system is billions of years older than the sun.

“We can think of water’s path through the universe as a trail,” said study lead author John Tobin, an astronomer at the National Science Foundation’s National Radio Astronomy Observatory (NRAO).

“We know what the endpoints look like, which are water on planets and in comets, but we wanted to trace that back to the origin of water.”

In the study, the astronomers discovered gaseous water in the planet-forming disk around the distant star V883 Orionis.

This water has a chemical signature that experts say explains water’s journey from star-forming gas clouds to planets like ours.

“We can now trace the origin of water in our solar system to before the formation of the sun,” Tobin added.

Stars form from dense molecular clouds — of dust and gas — in regions of interstellar space known as stellar nurseries.

If enough gas and dust converge in one region, it begins to collapse under the weight of its own gravity, forming a star in the center and a disk around it.

Over the course of a few million years, the matter in the disk clumps together to form comets, asteroids and eventually planets.

Tobin and his team used the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile to measure the chemical characteristics of the water and its path from the star-forming cloud to planets.

As is well known, water usually consists of one oxygen atom and two hydrogen atoms.

However, Tobin’s team studied a slightly heavier version of it, in which one of the hydrogen atoms has been replaced with deuterium – a heavy isotope of hydrogen.

This is useful because simple and heavy water are formed under different conditions, meaning their ratio can be used to trace where and when the water was created.

It’s this ratio that has previously shown how the water on certain comets in the solar system is similar to water on Earth, indicating that comets may have brought the liquid to our planet.

The journey of water from molecular clouds to young stars, and later from comets to planets, has been observed before, but until now the link between the young stars and comets has been missing.

“Until now, the chain of water in the development of our solar system had been broken,” Tobin said.

‘V883 Orionis is the missing link in this case. The composition of the water in the disc is very similar to that of comets in our own solar system.’

To connect the water in V883 Ori’s protoplanetary disk to that on Earth, the team of researchers used ALMA to determine that it remains relatively unchanged between each stage of the solar system’s formation: from protostar to protoplanetary disk and then Come eat.

“This confirms the idea that the water in planetary systems formed billions of years ago, before the sun, in interstellar space, and has been inherited by both comets and Earth, relatively unchanged,” Tobin said.

Study co-author Merel van ‘t Hoff, an astronomer at the University of Michigan, added: ‘This means that the water in our solar system formed long before the sun, planets and comets formed.

‘We already knew that there is a lot of water ice in the interstellar medium [but] pur results show that this water was absorbed directly into the solar system during its formation.

“This is exciting because it suggests that other planetary systems should have received large amounts of water as well.”

ALMA’s sensitivity and ability to discern fine detail allowed the researchers to both detect and determine the composition of water in V883 Orionis, and map its distribution within the disk.

From the observations, they found that the disk contains at least 1,200 times the amount of water in all of Earth’s oceans.

Margot Leemker, an astronomer at Leiden University and co-author of the study, said: ‘It is known that most of the water in the interstellar medium forms as ice on the surfaces of small dust particles in the clouds.

‘When these clouds collapse under their own gravity and form young stars, the water ends up in the discs around them.

‘Eventually the discs evolve and the icy dust particles clump together to form a new solar system with planets and comets.

She added: ‘We have shown that water produced in the clouds follows this track almost unchanged.

“So by looking at the water in the V883 Ori disk, we’re essentially looking back in time and seeing what our own solar system looked like when it was much younger.”

In the future, the astronomers hope to use the European Southern Observatory’s forthcoming Extreme Large Telescope to further strengthen their understanding of the path of water from star-forming clouds to solar systems.

They will do this by trying to identify how the water goes from ice to gas in these types of distant disks.

“This gives us a much more complete picture of the ice and gas in planet-forming discs,” added Leemker.

The research has been published in the journal Nature.