Researchers Shed Light on Birth of the First Stars
In the beginning, there were hydrogen and helium. Created in the first three minutes after the Big Bang, these elements gave rise to all other elements in the universe. The factories that made this possible were stars. Through nuclear fusion, stars generated elements such as carbon, oxygen, magnesium, silicon and the other raw materials necessary for making planets and ultimately life.
But how did the first stars come to be? New research from Columbia University shows that it all boils down to this simple reaction:
H- + H → H2 + electron
The research details a key chemical reaction that took place in the universe about a million years after the Big Bang. That reaction, called associative detachment, allowed clouds in the universe to cool, condense and form the first stars.
In order to understand how the first stars formed, we need to know how the clouds that gave birth to them cooled. Molecular hydrogen (H2) radiated the heat out of the clouds, so we need to know how much H2 was in the cloud. This in turn requires understanding the chemical process by which the H2 formed.
H2 is formed when two hydrogen atoms come together and bind to one another to make a molecule. The team measured this probability, with results showing that the likelihood for this is higher than previous theoretical calculations and experiments have shown.
The previous uncertainty in this reaction limited the ability to predict if a cloud of gas would form a star or not, and if it did, then what the mass of that star would be. That’s an important thing to quantify, because the mass of a star determines the elements it will synthesize.
The predicted masses for the first stars depend on the initial conditions of the primordial clouds from which they formed, which are highly uncertain and still an active area of research. By comparing model predictions to observations of the universe astronomers can approximate what these initial conditions must have been.
But the accuracy of these estimates depends critically on the understanding of the underlying chemical reactions. With the new data in hand, cosmologists will be better able to determine what the initial conditions were in the early universe leading to the formation of the first stars.
Image: A computer-generated model showing what the first star looked like. [+]
Source: Columbia University