By studying a nearby protostar, scientists discovered the presence of water in the star’s disk around it. New observations with the Atacama Large Millimeter/submillimeter Array (ALMA) mark the first detection of inherited water in the protoplanetary disk without significant changes in composition. These results also show that the water in our solar system formed billions of years before the sun. The new observations were published March 8 in the journal Nature.

The supplemental image shows the two types of water molecules being studied in this disc: regular water containing one oxygen atom and two hydrogen atoms, and a heavier version in which a hydrogen atom is replaced with deuterium, a heavy isotope of hydrogen.

V883 Orion is a protostar located about 1,305 light-years from Earth in the constellation Orion. New observations of this protostar have helped scientists find a possible link between water in the interstellar medium and water in our solar system, confirming that they have a similar composition.

“We can consider the path of water in the universe as natural. “We know what the extremes that are water on planets and comets look like, but we wanted to trace this path back to the origin of water,” said astronomer John Tobin of the National Science Foundation’s National Radio Astronomy Observatory (NRAO). “Previously, we could connect Earth to comets and protostars to the interstellar medium, but we could not connect protostars to comets. V883 Ori changed that and proved that the water molecules in this system and our solar system have a similar deuterium-to-hydrogen ratio.”

Water in the extrastellar disks around protostars is difficult to observe because water is present in most systems in the form of ice. When observing protostars, scientists look for a line of water snow or ice, where water often turns from ice to gas, and radio astronomy can observe in detail. “If the snow line is too close to the star, there isn’t enough gaseous water to be easily detected, and the dust disk can block most of the water emission. But if the snowline is further away from the star, there’s enough gaseous water to be detected, and that’s true for V883 Ori,” he said.

V883 Ori’s disk is quite large and so hot that the water inside turned from ice to gas. This makes this protostar an ideal target for studying the growth and evolution of solar systems at radio wavelengths.

“This observation highlights ALMA’s extraordinary ability to help astronomers study something vital to life on Earth: water,” said Joe Pesce, ALMA’s NSF program manager. “Understanding the deep processes important to us on Earth, observed in distant regions of the Galaxy, also benefits our knowledge of how nature works as a whole and the processes that must occur for our solar system to become what we are today.”