Astronomers are seeking to explore a little-studied time in our universe's history known as "the Dark Ages." The universe was dark in that no galaxies shined brightly as we see today. Yet somehow, out of this dark, mostly-hydrogen gas, the very first stars did form somehow, lighting up the cosmos for the very first time.
What these first stars were like is still a debate amongst astronomers since there is a lack of direct observations.
Astronomers can simulate the formation of stars under the conditions that were present in the very early universe. However, the scenario is complex on large and small scales and involves many physical and chemical processes, all which need to be tracked carefully.
Often, some assumptions and approximations must be made in order for the simulation to fit into a realistic computational space and time.
Many previous models of the first stars were semi-analytic, meaning that some processes were approximated through the use of equations, rather than just letting the simulation progress in a purely numerical way. These have long predicted that, in the absence of heavier elements such as carbon, nitrogen, and oxygen, that the first stars would be truly massive, reaching hundreds of times the mass of the sun before finishing their growth.
ANALYSIS: Following the Evidence to the First Stars
Such behemoths would live out very short lives and explode catastrophically in a type of supernova that is not seen in the universe today; a "pair-instability" supernova.
This collapse and subsequent explosion is so violent that it does not leave a black hole remnant behind, as other large supernovae do. However, the pattern of elements created by such a supernova should be detectable in the gas left over, now trapped in old "metal-poor" stars wandering the galaxy. (Remember, in this case, astronomers refer to "metals" as any element that is not hydrogen and helium. Sorry, chemists.)
The problem with this hypothesis up until now is that the pattern of elements in old, metal-poor stars does not match this prediction. Instead, it looks as if the gas was created in "regular" core-collapse supernovae that we still see today that herald the death of a star that is tens of times the mass of our sun. This explosion leaves behind a neutron star or black hole as a remnant.