Astronomers find missing link for origin of water in solar systems
An international team of astronomers, including astronomers from Leiden University, has found the missing link in the path taken by water through star-forming clouds and young stars to comets and planets. They did so with the help of the ALMA observatory in Chile. The researchers published their findings Wednesday evening in the journal Nature.
When a cloud of gas and dust collapses in the universe, a star forms at its centre. Around the star orbits a disk of gas and dust. The material in the disc clumps together over several million years to form comets, asteroids and eventually planets.
Ratio of water to heavy water
Astronomers have previously discovered water around stars, disks, comets and planets, but until now, data on the exact ratio of water to heavy water in the disk of gas and dust orbiting a young star was lacking. From the ratio of water (H2O) to heavy water (HDO), astronomers can deduce when and where water formed.
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Astronomers have now found water and heavy water in the disc around the star V883 Orionis, about 1,300 light years from Earth in the constellation Orion. The disc of V883 Orionis is, for yet unknown reasons, warmer than similar discs. ‘As a result, water is no longer icy but gaseous and we can detect that with telescopes,’ says John J. Tobin, astronomer at the National Radio Astronomy Observatory in the US and lead author. Tobin was a researcher at Leiden University from 2014 to 2016.
Beginning and end
Using the Atacama Large Millimetre/submillimetre Array (ALMA), the astronomers were not only able to detect the water, but also determine the ratio of water to heavy water and map its distribution within the disk.
The composition of water in the disk is very similar to that of cold star-forming clouds and comets in our own solar system. ‘So the ratio of heavy water to water is the same both at the beginning and at the end of the path that water travels,’ says co-author Margot Leemker, PhD student at the Leiden Observatory. ‘This confirms the idea that water is already formed in interstellar space and that it ended up on comets and planets relatively unchanged. At our sun and at our Earth, water has also probably taken this route.’
In the future, the researchers want to study the path of water in more detail. One way to do this is with the Extremely Large Telescope under construction and the associated METIS instrument being developed under the leadership of the Netherlands.