In a study published online today in the journal Science, it appears that much of the water in the solar system likely predates the birth of the sun according to lead writer Ilse Cleeves, an astronomy Ph.D. student at the University of Michigan.
That is water that is found in the Earth’s ocean, frozen in the moon’s craters and in meteorites is all sorts of old and originated in the cold interstellar cloud of gas that also led to the formation of the sun.
“The implications of our study are that interstellar water-ice remarkably survived the incredibly violent process of stellar birth to then be incorporated into planetary bodies,” writes Cleeves.
“If our sun’s formation was typical, interstellar ices, including water, likely survive and are a common ingredient during the formation of all extrasolar systems,” Cleeves added. “This is particularly exciting given the number of confirmed extrasolar planetary systems to date — that they, too, had access to abundant, life-fostering water during their formation.”
With that sentence she was certainly referring to the nearly 2,000 exoplanets that astronomers have found so far with many more (billions?) laying outside the limits of human detection but it’s widely believed that each star in the Milky Way has at least one exoplanet hanging around it.
Let’s move away from Cleeves for a moment to understand the reasons for the study.
“Why is this important? If water in the early solar system was primarily inherited as ice from interstellar space, then it is likely that similar ices, along with the prebiotic organic matter that they contain, are abundant in most or all protoplanetary disks around forming stars,” study co-author Conel Alexander, of the Carnegie Institution for Science in Washington, D.C., said in a statement.
“But if the early solar system’s water was largely the result of local chemical processing during the sun’s birth, then it is possible that the abundance of water varies considerably in forming planetary systems, which would obviously have implications for the potential for the emergence of life elsewhere,” Alexander added.
The models the water study used
We’re not necessarily speaking of water as we know it. Rather some water molecules contain deuterium a “heavy” isotope of hydrogen (one proton, one neutron) rather than the element hydrogen which contains the hydrogen isotope, Protium which has no neutrons.
As the two have different masses they behave differently during chemical reactions. So the researchers constructed models that simulated reactions in a protoplanetary disk reasoning that they could conclude if the concentrations of heavy water in Earth’s oceans and meteorite sample could have been generated in the early days of the solar system.
The researchers reset deuterium levels to zero at the beginning of the simulations, this was done to determine the amoun of deuterium-enriched ice could be produced within 1 million years. The 1 million years wasn’t an arbitrary number but the standard lifetime for planet-forming disks. And they found it could not, thus 30% to 50% of the water in the Earth’s oceans predated the birth of the sun.
“A significant fraction of Earth’s water is likely incredibly old, so old that it predates the Earth itself,” Cleeves said. “For me, uncovering these kinds of direct links between our daily experience and the galaxy at large is fascinating and puts a wonderful perspective on our place in the universe.”
So put on your Pink Floyd again and ask, “Is there anybody out there?”