New insights into the origin of water in the solar system

Where does water come from on Earth? how old? Researchers have observed a star 1,300 light-years away – and gained new insights.

Astronomers have discovered a crucial link in the origin of water on Earth. As reported by the science journal Scinexx, researchers have succeeded in detecting water molecules near a star 1,300 light-years away, which have similar properties to water in the solar system. “This supports the idea that water in planetary systems originated in interstellar space and was captured relatively unchanged by both comets and Earth,” says John Tobin of the National Radio Astronomy Observatory in Charlottesville, USA.

Astronomers have long suspected that at least some of the water in the solar system has an interstellar origin. “We can think of the water’s path through the universe as a chain,” Tobin explains. Its final members are already known to researchers. “So far, we have been able to connect Earth with comets and protostars to the interstellar medium,” says the first author of the study. “But the link from protostars to comets was missing.”

The protostar the researchers have now observed provides the missing link. Using the ALMA telescope in Chile, Tobin and his team analyzed gaseous water in the star’s disk. Thus the chemical signature of the molecules is similar to the water of comets in our solar system as well as the interstellar medium.

“This supports the idea that water in planetary systems originated in interstellar space and that both comets and Earth were taken over relatively unchanged,” says Tobin. The results were published in the journal Nature.

By looking at the water in the protostar’s disk, the researchers are “essentially looking back in time and seeing what our solar system looked like when it was much younger,” says Margot Liemker, co-author of the study. At the same time, the results showed that parts of the water on Earth could be much older than the Sun.