Astronomers have use the Atacama Large Millimeter/submillimeter Array (ALMA) to discover gaseous water in the planet-forming disc around the star V883 Orionis. The water they have discover carries a chemical signature that can explain the journey of water from star-forming gas clouds to planets.
It also supports the idea that the water on earth is even older than the Sun.
Stars are form from the clouds of dust and gas, or nebulae, that inhabit our universe.
When such clouds collapse in on themselves, a star begins forming at their centre.
And when this happens, the material from the cloud forms a disc around the “protostar.”
So, over a period of millions of years, the matter in the disks clump together to form comets, asteroids and even planets.
The Astronomers team, which is part of the European Southern Observatory, (ESO) use ALMA to measure the chemical signatures of the water around V883 Orionis.
Normally, water consists of one oxygen atom and two hydrogen atoms.
The ESO researchers studies a heavier version of water where one of the hydrogen atoms is replace with deuterium, which is a heavy isotope of hydrogen.
Normal water and this kind of heavy water exist under different conditions.
That means the ratio between the two can be use to trace when and where the water was form.
Let take a example, the ratio of water to heavy water in some comets in the solar system are similar to that of water on Earth.
This suggests that comets could have deliver water to our planet.
According to ESO, the journey of water from clouds to young stars, and then to comets and planets has previously observe.
But until this discovery, scientists found it difficult to pin down the link between young stars and comets.
John J. Tobin, an astronomer at the National Radio Astronomy Observatory, USA and lead author of the study publish in the journal Nature, said in a press statement :
An earlier study had already suggest that more than half the water on our planet is older than the Sun, but this new study suggests that all the water on the planet is older than the Sun
But observing the water around V883 Orionis was not easy.
As per study co-author Margot Leemker, most of the water in planet-forming discs is frozen, which means that it is hidden from the astronomers’ view.
But as luck would have it, a recent study show that the V883 Orionis disc was unusually hot due to a dramatic outburst of energy from the star.
This energy heats up the water to the point that it is no longer in the form of ice but in the form of gas.
Not like a frozen water, gaseous water can be detect due to the radiation emitted by molecules as they spin and vibrate.
When water is frozen, this is more complicate because the motion of molecules is much more constrain.