The new results show definitively that a substantial portion of the water on Earth most likely formed billions of years ago, before the Sun had even ignited. These results fill in the gap of the water trail forging a direct link between water in the interstellar medium, protostars, proto-planetary disks and planets like Earth through the process of inheritance, not chemical reset. We measured the ratio of semi-heavy to normal water and found that the ratio was very similar to ratios found in comets as well as the ratios found in younger protostar systems.

The data revealed a strong signature of semi-heavy and normal water coming from V883 Ori’s proto-planetary disk.

In 2021, the Atacama Large Millimeter/submillimeter Array took measurements of V883 Ori for six hours. V883 Ori emits 200 times more energy than the Sun, and my colleagues and I recognized that it was an ideal candidate to observe the semi-heavy to normal water ratio. Using the Atacama Large Millimeter/submillimeter Array, a powerful radio telescope in northern Chile, we discovered a large, warm proto-planetary disk around the Sunlike young star V883 Ori, about 1,300 light years from Earth in the constellation Orion. Due to this higher energy output, the proto-planetary disks around FU Orionis stars are heated to much higher temperatures, turning ice into water vapor out to large distances from the star. FU Orionis stars are unique because they consume matter about 100 times faster than typical young stars and, as a result, emit hundreds of times more energy. Most young stars consume matter from the proto-planetary disks around them. It is possible to detect semi-heavy and normal water when water is a gas unfortunately for astronomers, the vast majority of proto-plantary disks are very cold and contain mostly ice, and it is nearly impossible to measure water ratios from ice at interstellar distances.Ī breakthrough came in 2016, when my colleagues and I were studying proto-planetary disks around a rare type of young star called FU Orionis stars. Doing so has proved to be incredibly difficult. To truly determine where the water on planets comes from, astronomers needed to find a goldilocks proto-planetary disk – one that is just the right temperature and size to allow observations of water. Earth’s ratio sits somewhere in between the inheritance and reset ratio, making it unclear where the water came from.

Measuring water during the formation of a planetĬomets have a ratio of semi-heavy to normal water almost perfectly in line with chemical inheritance, meaning the water hasn’t undergone a major chemical change since it was first created in space. The process continues and eventually forms the familiar objects of space like asteroids, comets, rocky planets like Earth and gas giants like Jupiter or Saturn. Astronomers call this a proto-planetary disk.Īs icy dust particles collide with each other inside a proto-planetary disk, they begin to clump together. Since only a small fraction of the gas initially collapses into the newborn protostar, the rest of the gas and dust forms a flattened disk of material circling around the spinning, newborn star. Stars begin to form when parts of the collapsing cloud reach a certain density and heat up enough to start fusing hydrogen atoms together. As the density of these clouds increases, atoms begin to collide more frequently and form larger molecules, including water that forms on dust grains and coats the dust in ice. Due to gravity, some pockets of the interstellar medium will become more dense as particles attract each other and form clouds. The so-called “emptiness of space” – or the interstellar medium – in fact contains large amounts of gaseous hydrogen, smaller amounts of other gasses and grains of dust. The formation of stars and planets is intertwined.

A step back in time eso