Earth’s Water Traced Back To Stellar Nursery 1,300 Light Years Away
Earth’s oceans, rivers and lakes have been traced back to a stellar nursery 1,300 light years away.
Astronomers describe it as the missing link in the origins of life as we know it.
The key ingredient of water formed in a distant galaxy – and is even older than our sun.
Lead author Dr. John Tobin, of the National Radio Astronomy Observatory, said: “We can now trace the origins of water in our Solar System to before the formation of the sun.”
The international team detected gaseous water in a massive planet-forming disc around the star V883 Orionis.
It lies in the constellation of Orion in the southwestern sky and was scanned by the ALMA (Atacama Large Millimeter/submillimeter Array) telescope in Chile.
From the observations, they found this disc contains at least 1,200 times as much water as in all Earth’s oceans.
It could help alien hunters identify planets or moons most like to host extra-terrestrials.
The journey of water from clouds to young stars, and then later from comets to planets has previously been observed.
But the pathway between young stars and comets has been a mystery – until now.
Tobin said: “V883 Orionis is the missing link in this case.
“The composition of the water in the disc is very similar to that of comets in our own Solar System.
“This is confirmation of the idea that the water in planetary systems formed billions of years ago, before the Sun, in interstellar space, and has been inherited by both comets and Earth, relatively unchanged.”
But observing the water turned out to be tricky because the motion of molecules is constrained when it is frozen.
Co-author Margot Leemker, a PhD student at Leiden Observatory in the Netherlands, explained: “Most of the water in planet-forming discs is frozen out as ice, so it’s usually hidden from our view.”
Gaseous water can be detected thanks to the radiation emitted by molecules as they spin and vibrate.
It can be found towards the center of the discs, close to the star, where it’s warmer.
However, these close-in regions are hidden by the dust itself, and are also too small to be imaged with our telescopes.
Fortunately, the V883 Orionis disc is unusually hot thanks to a dramatic outburst of energy from the star.
It 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 Tobin.
ALMA’s sensitivity and ability to discern small details even enabled the water to be mapped within the disc.
It’s hoped the upcoming Extremely Large Telescope will track water all the way from star-forming clouds to solar systems.
Leemker said: “This will give us a much more complete view of the ice and gas in planet-forming discs.”
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