The new observations of a pre-stellar core–or cold, dark clouds of gas and dust–in the constellation of Taurus are the first detection of water vapor in a molecular cloud on the verge of star formation.
“To produce that amount of vapor, there must be a lot of water ice in the cloud, more than three million frozen Earth oceans’ worth,” Paola Caselli from the University of Leeds, UK, lead author of the paper reporting the results in Astrophysical Journal Letters, said in a press release.
“Before our observations, the understanding was that all the water was frozen onto dust grains because it was too cold to be in the gas phase and so we could not measure it.”
Caselli said that the astronomers now need to review their understanding of the chemical processes in this dense region, and the importance of cosmic rays to maintain some amount of water vapor.
ESA said the observations also revealed that the water molecules are flowing towards the heart of the cloud where a new star will likely form. This could indicate that gravitational collapse has just started.
“There is absolutely no sign of stars in this dark cloud today, but by looking at the water molecules, we can see evidence of motion inside the region that can be understood as collapse of the whole cloud towards the centre,” Caselli said in the release. “There is enough material to form a star at least as massive as our Sun, which means it could also be forming a planetary system, possibly one like ours.”
Some of the water vapor detected will go into forming the star, but the rest will be incorporated into the surrounding disc.
“Thanks to Herschel, we can now follow the ‘water trail’ from a molecular cloud in the interstellar medium, through the star formation process, to a planet like Earth where water is a crucial ingredient for life,” ESA’s Herschel project scientist, Göran Pilbratt, said in the press release.
These pre-stellar cores contain all the ingredients to make up solar systems such as our own.
Water has previously been detected in other places outside of our Solar System as gas and ice coated on tiny dust grains near sites of active star formation, and in proto-planetary discs capable of forming alien planetary systems.