Until a few decades ago, the presence of water was thought to be unique on Earth, and it was actually used as a biosignature – biosignatures are defined as objects, substances, or variations in time that require a biological agent.
Until now, it was thought that the presence of water on celestial bodies was an index of life, because it was precisely in this liquid that the first organisms appeared on the planet.
We know today that water is not necessarily a biosignature and that it is instead a compound present in many bodies, not only in the solar system but also in deep space.
Planets, asteroids, comets and even our Moon all have water on their surface, but the explanation of how this compound was generated in the cosmos remains a mystery to astrochemists and astrobiologists.
The water cycle in the cosmos
Water was known to pass from gas clouds to planet-forming disks in young stars, and then from comets to planets. However, there is a missing link in this understanding of the water cycle in the cosmos that does not predict how water moves from young stars to comets.
The latest discovery, made by a team of researchers led by John J. Tobin of the National Radio Astronomy Observatory the United States, suggests that the “missing link” in determining the origin of water has finally been found.
Using the ALMA telescope in Atacama, Chile, the team detected the presence of gaseous water in the planet-forming disc around the star V883 Orionis, located 1300 light years from Earth.
When a cloud of gas and dust is generated in the Universe, it tends to collapse under the effect of gravity, leading to the formation of a star in its center. The result is a star surrounded by a disk called a “planet-forming disk” because it is the nest of asteroids and planets that will later take shape.
Scientists have discovered water in the disk surrounding the protostar V883 Orionis, suggesting that water in the Solar System formed billions of years before the Sun. https://t.co/Wu8fqUGtrB
— Canaltech (@canaltech) March 8, 2023
Tobin and his team were analyzing planet-forming disc V883 Orionis when they discovered particles of a type of carbonated water that is similar in chemical composition to water on Earth.
On Earth, water is usually made up of two hydrogen atoms and one oxygen atom, but the version found by Tobin and his team is slightly heavier, one of the two hydrogen atoms being replaced by deuterium, a heavy isotope of hydrogen.
This type of chemical composition provides valuable information to astrochemists, because simple water and heavy water are formed under different conditions, so that it is possible to determine when and where the compound formed.
Water is older than the sun
The quantity of water measured around V883 Orionis is impressive: according to the researchers, there is enough water to fill our oceans 1200 times. But that’s not all ! Its composition is also similar to that of comets in the solar system, suggesting that the compound would have frozen in the clouds of the planetary disk and then clumped together as comets.
This team of researchers discovered water in a gaseous state in a star located 1300 light years from Earth, which allowed them to conclude that it is older than our Sun and, therefore, that our solar system.
The results of the study are simply staggering, because they prove that water is even older than our sun and therefore the solar system itself. The water that gave life to water formed in space and then ended up on Earth via comets.