How soon after the big bang did the first water form? This is an important question in the search for life “out there” because all of the life we currently know of is dependent on water.
We know that water could not have been present in the early universe because oxygen was first formed in the original generation of stars. That oxygen then had to be disbursed and mix with hydrogen under the right conditions.
New theoretical research has now shown that water vapor could have been plentiful, as plentiful as it is today, in some regions as early as one billion years after the Big Bang.
“We looked at the chemistry within young molecular clouds containing a thousand times less oxygen than our Sun. To our surprise, we found we can get as much water vapor as we see in our own galaxy,” says astrophysicist Avi Loeb of the Harvard-Smithsonian Center for Astrophysics (CfA) in a statement.
The first generation of stars following the Big Bang were formed from hydrogen and helium. These stars are thought to have been massive but short-lived. The nuclear reactions within those stars generated heavier elements, including oxygen, which then spread out through solar winds, flares and eventually supernovae.
The gas clouds, or islands, that formed from those elements were still very oxygen poor at least when compared to younger galaxies like the Milky Way. Although oxygen was more scarce, the universe was also a warmer place at that time. The researchers found that at temperatures of 80 degrees Fahrenheit, large amounts of gaseous water could form.
“These temperatures are likely because the universe then was warmer than today and the gas was unable to cool effectively,” said Shmuel Bialy PhD student at Tel Aviv University and lead author of a paper on the topic, accepted for publication by the journal Astrophysical Journal Letters and currently available online.
“The glow of the cosmic microwave background was hotter, and gas densities were higher,” added Amiel Sternberg, a co-author from Tel Aviv University.
According to the researchers, ultraviolet light might break apart water molecules but, given hundreds of millions of years, an equilibrium between the formation and destruction of molecules could be reached.
“You can build up significant quantities of water in the gas phase even without much enrichment in heavy elements,” said Bialy.
This study is only concerned with the formation of water in the gas phase that would form later generations of stars and planets and not with water ice.
Water in some form exists on almost every body of any size studied in our solar system and appears to dominate many of the observed exoplanets. This research, however, puts something of a timeline on when water first appeared in the universe and so provides information on where we might look for life “as we know it”.
