Washington, July 10: Not much is known about the universe’s first stars. But, a new study has now claimed that up to half of the ancient beacons may have been born in pairs.
And, according to planetary scientists, born together in clouds of gas, many of these stars might have been smaller than previously thought, which may resolve why so far no proof has been found for exotic physical processes thought to occur in super-heavy stars from the early universe.
The findings may also mean the population III star pairs could be detected by the gravitational waves they would emit at the end of their lives, the New Scientist reported.
Lead scientist Matthew Turk of the Kavli Institute for Particle Astrophysics and Cosmology in California said: .
“Multiple star formation had been proposed as a mechanism for forming the first stars in the universe, but this is the first time we’ve seen it in cosmologically realistic conditions.”
The scientists simulated the conditions 20 million years after the Big Bang, when the universe was a soup of mostly hydrogen and helium gas. They ran five simulations — each with slightly different initial conditions, such as the distribution of knots of gas that could seed star formation.
The simulations modelled what would happen over the first 190 million years after the Big Bang, enough time for gravity and cooling gas to condense down into cores of dense gas that could eventually evolve to form stars. In one simulation, the team was surprised to see that a cloud had fragmented to form two such cores. Like pizza dough, the spin of the cloud seemed to contribute to tearing it apart.
Hydrogen molecules created as the cloud collapsed gravitationally also helped cool the gas, enabling it to clump up even more easily.
Many more simulations will be needed to reveal just how common population III star pairs might be. The fraction of the stars that are born in pairs is “probably less than half but probably more than 5 per cent”, Turk said.
“Finding that population III stars can be born in pairs nicely makes this discrepancy go away which is really exciting,” said co-scientist Brian O’Shea of Michigan State University.
–PTI