A solar system like our own forms from huge clouds of dust and gas that collapse in on themselves, forming stars and planetary systems. An intriguing discovery has been made by Leeds physicist and astro-chemist Paola Caselli, on the search for water in our universe and its implications.
The search for water has been an exciting one, there is strong evidence that salt water flows on Mars, frozen ice is in deep craters of Mercury, and comets keep water dating back to the beginning of the solar system in pristine safes. Where does this water come from and what makes this discovery so special? Professor Caselli explains, “With the observations of water in the gas phase, in a cloud we know will form a star similar to our sun and probably a planetary system similar to ours, what we can do for the first time is we can measure how much water there is just before a star and planetary system is formed. In the gas phase there are about 2 thousand Earth oceans of water vapor, and from chemical models this means 3 million frozen oceans. The main point is that there is already a lot of water available to seed future planets at the dawn of star formation.”
Water plays a vital role in the formation of other more complicated molecules, in the search for life and in understanding life’s origins, especially as Caselli describes, when it comes to planet formation, “The water we have seen comes from the icy mantles of dust grains, which will then coagulate and form pebbles within protoplanetary disks. These pebbles will then become planetesimals and ultimately planets. So, we believe the water reservoir we deduce from our observations is most likely the one that will seed new planets.”
The amount of water found in L1544 suggests that there is no need to form any other water once the star is formed. A key feature of this discovery is that water in its gas form was found. Professor Caselli states,“Most of the astronomers were skeptical, because water was expected to be completely frozen at the center of dense clouds”. Not only did they find see it as a gas, but from its line profile they could positively detect something was happening,“we unveiled the contraction motion…because of the movements in the cloud you have some redshift (changes in the frequency of light as the object moves away from us, and becomes more red), and some blueshift (changes as it moves towards us, the light becoming more blue) because the cloud is contracting”
For the first time a cloud on the brink of collapse has been observed, L1544 is on the move, it is collapsing inward, the very beginnings of a new star in the making, and the water in it may end as oceans on a very similar planet to our own.
Rosa Jesse