Astronomers have discovered gaseous water in the planet-forming disc around the star V883 Orionis using the Atacama Large Millimeter/submillimeter Array (ALMA). The said water has a chemical signature that explains how water gets from star-forming gas clouds to planets in the Solar System and supports the theory that water on Earth is even older than the Sun.
Tracing the Origin of Water on Earth
Astronomer John J. Tobin of the National Radio Astronomy Observatory in the US, the study's lead author, said in the press release that their findings allow them to trace the origin of water on Earth and the Solar System as a whole to a time before the Sun was formed.
The team studied water composition in the planet-forming disc called V883 Prionis about 1,300 light-years away from Earth. They found a star at the center surrounded by material from the cloud that also forms a disc.
The matter in the disc clumped over the course of a few million years and formed comets, asteroids, and eventually planets. Researchers used the European Southern Observatory (ESO) ALMA telescope to measure chemical signatures of water and its path to the planets from the planet-forming disc.
Researchers noted that water typically comprises one oxygen atom and two hydrogen atoms. But the team looked at a heavier form of water that has deuterium in replacement of one hydrogen atom. Deuterium is a heavy isotope of hydrogen.
In their study, titled "Deuterium-enriched Water Ties Planet-forming Disks to Comets and Protostars" published in the journal Nature, researchers wrote that the ratio of the simple and heavy water may be used to identify when and where water formed as they occur under distinct conditions.
Previous studies established that this ratio on Earth is similar to comets in the Solar System, which implies that these space rocks may have brought water to Earth. However, the link between young stars and comets is still missing.
Tobin said that V883 Orionis is this missing link that will point to the origin of water on Earth. The composition of water in the disc is so similar to comets in the Solar System, confirming the idea that water in the planetary system formed billions of years ago even before the Sun.
Water in Planet-forming Disc is Frozen
Astronomers also wrote in their study that observing water in planet-forming disc is a bit of a challenge just like how scientists would attempt to study a star's composition some 1,300 light-years away, BBC's Sky at Night Magazine reported.
Margot Leemkr, a Ph.D. student at Leiden Observatory in the Netherlands and a co-author of the study, explained that water in planet-forming discs is frozen out so it is usually hidden from view. But as gaseous water, it can be easily detected since the molecules are able to spin and vibrate to generate radiation that can be studied using a powerful telescope.
V883 Orionis' outer part is frozen as ice and cannot be easily detected. But the outburst from the star itself at the center of the disc turns the water into its gaseous form which makes it detectable.
Through the ALMA observations, scientists were able to study the chemical composition of the gaseous water on V883 Orionis and helped them analyze its composition, as well as map its distribution in the disc. Based on observations, they found that it contains 1,200 times the amount of water on Earth.
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