Astronomers have made a groundbreaking discovery that could shed new light on the origins of water on Earth. Using the Atacama Large Millimeter/submillimeter Array (ALMA), scientists detected gaseous water in the planet-forming disc around the star V883 Orionis, located about 1,300 light-years away from Earth.
According to the researchers, the detection of water supports the idea that water on Earth is even older than our Sun. In fact, the team behind the study said they were able to trace the origins of water in our Solar System to before the formation of the Sun.
The study, which has been published in the scientific journal Nature, provides new insights into the journey of water from star-forming gas clouds to planets.
When a cloud of gas and dust collapses, it forms a star at its center, and around the star, material from the cloud forms a disc. Over millions of years, the matter in the disc clumps together to form comets, asteroids, and eventually planets.
To trace the origins of water in the V883 Orionis disc, the scientists measured the chemical signatures of the water and its path from the star-forming cloud to planets using ALMA. Water typically consists of one oxygen atom and two hydrogen atoms. The researchers studied a slightly heavier version of water where one of the hydrogen atoms is replaced with deuterium, a heavy isotope of hydrogen.
By studying the ratio of simple and heavy water, the researchers were able to trace when and where the water was formed. In some Solar System comets, the ratio has been shown to be similar to that in water on Earth, suggesting that comets might have delivered water to Earth.
The scientists used ALMA, an array of radio telescopes in northern Chile, to observe the gaseous water in V883 Orionis. From the observations, the scientists found that the disc contained at least 1,200 times the amount of water in all of Earth's oceans.
The discovery of gaseous water in the planet-forming disc around V883 Orionis is significant because most of the water in planet-forming discs is frozen out as ice, making it hidden from view. Gaseous water can be detected thanks to the radiation emitted by molecules as they spin and vibrate. But this is more complicated when the water is frozen, where the motion of molecules is more constrained.
Fortunately, the V883 Orionis disc was shown in a recent study to be unusually hot. A dramatic outburst of energy from the star heats the disc "up to a temperature where water is no longer in the form of ice, but gas, enabling us to detect it," said lead author John J. Tobin, an astronomer at the National Radio Astronomy Observatory in the US.
Tobin said that the composition of the water in the V883 Orionis disc is very similar to that of comets in our own Solar System, confirming the idea that the water in planetary systems formed billions of years ago, before the Sun, in interstellar space. The water has been inherited by both comets and Earth, relatively unchanged.
In conclusion, the discovery of gaseous water in the planet-forming disc around V883 Orionis is a significant breakthrough in the study of the origins of water on Earth. It provides new insights into the journey of water from star-forming gas clouds to planets and suggests that water on Earth is even older than our Sun. Further studies will be needed to confirm these findings and shed more light on the mysteries of our universe.