Water in the form of gas detected in a forming solar system

The “missing link” that would explain the abundance of water in the solar system finally been discovered?

Artistic illustration showing the planet-forming disc around the star V883 Orionis. The inset image shows the two types of water molecules studied in this disc.

By analyzing data collected by the ALMA (Atacama Large Millimeter/Submillimeter Antenna Array) telescope of the European Southern Observatory (ESO) installed in Chile, an international team of astrophysicists has detected #x27;water in a gaseous state in V883 Orionis, a planet-forming disc located about 1300 light-years from Earth.

Water bears a signature chemical that traces its journey from the gas clouds where the star is formed to the planets, note in a press release the authors of this work published in the journal Nature (in English ).

This diagram illustrates how a cloud of gas collapses to form a star with a disk around it, from which a planetary system will eventually form.

This discovery supports the x27;the idea that water on Earth is even older than our Sun, says astronomer John J. Tobin of the US National Radio Astronomy Observatory.

“We can now trace the origins of water in our solar system to before the formation of the Sun.

— John J. Tobin, astronomer at the US National Radio Astronomy Observatory

• A star is born as a result of the collapse of a cloud of gas and of dust.
• The remaining matter then forms a disc around the star.
• In the millions of years that follow, the material in the disc is accreted to form asteroids, comets and planets.

Usually, water consists of one oxygen atom and two hydrogen atoms.

In their study, the scientists studied the presence of a slightly heavier version of water where one of the hydrogen atoms is replaced by deuterium – a heavy isotope of hydrogen.

Because simple water and heavy water do not form under the same conditions, researchers were able to use their proportion to determine when and where it formed.

“For example, this proportion in some solar system comets has been shown to be similar to that of water on Earth, leaving to think that comets may have brought water to Earth.

—John J. Tobin, astronomer at the U.S. National Radio Astronomy Observatory

Other work has already observed the travel of water from clouds to young stars, then from comets to planets. However, until now, the link between young stars and comets has been missing.

According to data collected by the researchers, the composition of water in the disc is very similar to that of comets in our own solar system.

According to them, this reality confirms the idea that the water of planetary systems formed billions of years ago, before the Sun, in interstellar space, and that comets and Earth inherited relatively unchanged.

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Water in planet-forming disks is usually frozen as ice. It is therefore usually hidden from view, says Margot Leemker, co-author of the study and a doctoral student at the Leiden Observatory in the Netherlands.

For its part, water in a gaseous state can be detected thanks to the radiation emitted by the molecules when they rotate and vibrate, but this is more complicated when the water is frozen, the movement of the molecules being more constraining.

Gas water can be detected towards the center of the disks, near the star, where it is hotter. But these regions are often hidden by the dust disk itself, and are also too small to be seen with current telescopes.

This was before a recent study showed that the disk of V883 Orionis was exceptionally hot due to a spectacular burst of energy from the star to a temperature where the water is no longer in the form of ice, but of gas, which allows us to detect it, notes John J. Tobin.

This detection was made possible thanks to to the sensitivity and ability to discern small details of the ALMA radio telescope array.

Scientists were thus able to both detect water and determine its composition, as well as map its distribution in the disc.

Their observations determined that this disc contains at least 1200 times the amount of water in all of Earth's oceans.

Recall that 13 planets, including 5 dwarfs, orbit around our star, the Sun, and that at least 171 moons revolve around these planets. There are also over 3000 comets and millions of asteroids in our solar system alone. This is our cosmic neighborhood, since our Sun is in a galaxy, the Milky Way, which itself contains a few hundred billion stars. And there are billions of galaxies in the Universe.

In the next few years, Margot Leemker and John J. Tobin hope to study the disc of V883 Orionis using the METIS instrument of the future Giant European Telescope (TGE) which must enter service by 2027.

This instrument will be able to scrutinize the gaseous phase of water in these types of discs, strengthening the link between the course water from star forming clouds to solar systems.

This will give us a much more complete view of ice and gas in planet formation discs, says Margot Leemker.