Astonishing Discovery Reveals Water in Our Solar System May Have Originated Billions of Years Before the Sun

V883 Ori is an extraordinary protostar that boasts a temperature that is hot enough to turn water in its circumstellar disk into gas. This gas can be studied by radio astronomers to trace the origin of water. Recently, ALMA observations have verified that the water in our Solar System may have the same source as the water found in the disks surrounding protostars in other parts of the Universe – the interstellar medium. Credit: ALMA (ESO/NAOJ/NRAO), B. Saxton (NRAO/AUI/NSF)

ALMA traces the history of planet-forming water in the interstellar medium

Observations of water in the disk forming around the protostar V883 Ori have revealed clues about the formation of comets and planetesimals in our solar system.

Scientists studying a nearby protostar have discovered the presence of water in its circumstellar disk. The new observations made with the Atacama Large Millimeter/submillimeter Array (ALMA) mark the first detection of water being inherited in a protoplanetary disk without significant changes in its composition. These results further suggest that the water in our Solar System formed billions of years before the Sun. The new observations were published on March 8 in the journal Nature.

This artist’s impression shows the planet-forming disk around the star V883 Orionis. In the outermost part of the disk, the water is frozen as ice and therefore cannot be easily detected. A burst of energy from the star heats the inner disk to a temperature where water is gaseous, enabling astronomers to detect it.
The inset image shows the two types of water molecules studied in this disk: normal water, with one oxygen atom and two hydrogen atoms, and a heavier version where one hydrogen atom is replaced by deuterium, a heavy isotope of hydrogen.
Credit: ESO/L. Calçada

V883 Orionis is a protostar located approximately 1305 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 similar compositions.

V883 Ori is a unique protostar whose temperature is hot enough that the water in its circumstellar disk has turned to gas, making it possible for radio astronomers to trace the origin of the water. New observations with the Atacama Large Millimeter/Submillimeter Array (ALMA) have provided the first confirmation that water in our Solar System may come from the same place as water in disks surrounding protostars elsewhere in the Universe: the interstellar medium. Credit: ALMA (ESO/NAOJ/NRAO), B. Saxton (NRAO/AUI/NSF)

“We can think of the path of water through the Universe as a path. We know what the endpoints look like, which are water on planets and comets, but we wanted to trace that back to the origin of water,” said John Tobin, an astronomer at the National Science Foundation’s National Radio Astronomy Observatory ( NRAO). and lead author on the new paper. “Previously, we could connect Earth to comets and protostars to the interstellar medium, but we couldn’t connect protostars to comets. V883 Ori has changed that and proved that water molecules in that system and in our solar system they have a similar ratio of deuterium to hydrogen.

Using ALMA, astronomers have detected the chemical signature of gaseous water in the planet-forming disk V883 Orionis. This acts as a time stamp for the water’s formation, allowing us to track its journey. Credit: ESO

Observing water in circumstellar disks around protostars is difficult because in most systems water is present in the form of ice. When scientists observe protostars, they are looking for the water snow line, or ice line, which is where water transitions from ice to mostly gas, which radio astronomy can observe in detail. “If the snowline is very close to the star, there is not enough gaseous water to be easily detected, and the dusty disk can block much of the water emission. But if the snowline is further away from the star, there is enough gaseous water to be detected, and that is the case with V883 Ori,” said Tobin, who added that the unique state of the protostar is what made it possible. this project.

The disk of V883 Ori is massive enough and hot enough that the water in it has turned from ice to gas. This makes this protostar an ideal target for studying the growth and evolution of solar systems at radio wavelengths.

Most of the time, the water in the circumstellar disks surrounding protostars is in the form of ice, sometimes extending long distances from the star. In the case of V883 Ori, the snowline extends 80 au from the star; that’s 80 times the distance between Earth and the Sun, as shown in this animation. But the temperature in V883 Ori is hot enough that most of the ice in its disk has turned to gas, making it possible for radio astronomers to study that water in detail. New observations with the Atacama Large Millimeter/Submillimeter Array (ALMA) have revealed that the water in V883 Ori’s disk has the same basic composition as water in objects in our Solar System. This suggests that the water in our solar system formed billions of years before the Sun in the interstellar medium. Credit: ALMA (ESO/NAOJ/NRAO), J. Tobin, B. Saxton (NRAO/AUI/NSF)

“This observation highlights the excellent capabilities of the ALMA instrument to help astronomers study something vital to life on Earth: water,” said Joe Pesce, NSF Program Officer for ALMA. “An understanding of the fundamental processes important to us on Earth, seen in more distant regions of the galaxy, also benefits our knowledge of how nature works in general and the processes that had to occur for our Solar System to develop into what we know. we know. today.”

To relate the water in V883 Ori’s protoplanetary disk to that in our own solar system, the team measured its composition using ALMA’s Band 5 (1.6mm) and Band 6 (1.3mm) receivers and found that it remains relatively unchanged. between each phase. of the formation of the solar system: protostar, protoplanetary disk and comets. “This means that the water in our Solar System formed long before the Sun, planets and comets formed. We already knew that there is a lot of water ice in the interstellar medium. Our results show that this water was directly incorporated into the Solar System during its formation,” said Merel van ‘t’Hoff, an astronomer at the University of Michigan and a co-author of the paper. “This is exciting as it suggests that other planetary systems should also have received large amounts of water.”

While searching for the origin of water in our Solar System, scientists settled on V883 Orionis, a unique protostar located 1,305 light-years from Earth. Unlike other protostars, the circumstellar disk surrounding V883 Ori is hot enough that the water in it has turned from ice to gas, making it possible for scientists to study its composition using radio telescopes like those at the Large Millimeter Array /submillimeter of Atacama. ALMA). Radio observations of the protostar revealed water (orange), a continuum of dust (green) and molecular gas (blue) suggesting that the water in this protostar is remarkably similar to water in objects in our solar system and may have similar origins. Credit: ALMA (ESO/NAOJ/NRAO), J. Tobin, B. Saxton (NRAO/AUI/NSF)

Elucidating the role of water in the development of comets and planetesimals is essential to understanding how our solar system developed. Although the Sun is believed to have formed in a dense cluster of stars and V883 Ori is relatively isolated with no nearby stars, the two have one critical thing in common: they both formed in giant molecular clouds.

“Most of the water in the interstellar medium is known to form as ice on the surfaces of tiny dust grains in clouds. When these clouds collapse under their own gravity and form new stars, the water ends up in the disks around them. Eventually, the disks evolve and the icy dust grains coalesce to form a new solar system with planets and comets,” said Margot Leemker, an astronomer at Leiden University and a co-author of the paper. “We have shown that the water that is produced in the clouds follows this track practically unchanged. So by looking at the water in the V883 Ori disk, we’re essentially looking back in time and seeing what our Solar System looked like when it was much younger.”

V883 Orionis is a protostar located approximately 1305 light-years from Earth in the constellation Orion. Credit: ESO/IAU and Sky & Telescope

Tobin added, “Until now, the water chain in the development of our Solar System was broken. V883 Ori is the missing link in this case, and we now have an unbroken chain in the waterline from comets and protostars to the interstellar medium.”

For more on this discovery, see Water on Earth is even older than our sun.

Reference: “Deuterium-enriched water links planet-forming disks to comets and protostars” by John J. Tobin, Merel LR van ‘t Hoff, Margot Leemker, Ewine F. van Dishoeck, Teresa Paneque-Carreño, Kenji Furuya, Daniel Harsono , Magnus V. Persson, L. Ilsedore Cleeves, Patrick D. Sheehan, and Lucas Cieza, 8 March 2023, Nature.
DOI: 10.1038/s41586-022-05676-z