Back in 1967, NASA researchers discovered the gamma-ray bursts (GRBs) in an occurrence known as the ‘Vela Incident.’ Since then, they strove to determine the reason behind these bursts as well as the process that leads to them taking place.
Years of observation have conducted scientists to the conclusion that these explosions take place when a gigantic star goes supernova, but they are still unsure why it happened in some instances, but not in others. Thanks to a new research led by a team from the University of Warwick, it seems like the main factor in producing GRBs is found in binary star systems. This means that a star that produces the brightest explosion in the Universe needs a mate.
The Process Leading to a GRB
The team of researchers was led by Ashley Chrimes, a Ph.D. student at the University of Warwick Department of Physics. The scientists have focused on the central enigma about long-duration GRBs, which is how stars can be rotated sufficiently fast to produce that type of explosions that have been seen.
GRBs happen when gigantic stars go supernova and crush into a neutron star or black hole. In the process, the object’s outer sheets are expelled, and the material flattens down to resemble a disc surrounding the just-formed leftover to preserve angular momentum. As this material descends inwards, the momentum fires it as jets, appearing from the poles.
These are dubbed ‘relativistic jets,’ due to the way the component is accelerated to the speed of light. While GRBs are the most luminous events in the Universe, they can only be seen from Earth when one of their polar sides are pointed towards our planet.
Moreover, a star needs to be rotating extremely fast to expel material along its polar axes at almost the speed of light. To solve the mysteries, researchers based their study on a library of stellar evolution models to analyze the activity of gigantic stars as they explode.
It Needs to be a Binary System
These simulation models were designed by Dr. J.J. Eldridge from the University of Auckland, New Zealand, together with researchers from the University of Warwick. Using a method known as binary population synthesis, the astronomers simulated a population of thousands of star systems in order to detect the mechanism that produces the GRBs.
Chrimes explained in a press release:
“We’re predicting what kind of stars or systems produce gamma-ray bursts, which are the biggest explosions in the Universe. Until now, it’s been unclear what kind of stars or binary systems you need to produce that result.
“The question has been how a star starts spinning or maintains its spin over time. We found that the effect of a star’s tides on its partner is stopping them from slowing down, and, in some cases, it is spinning them up. They are stealing rotational energy from their companion, a consequence of which is that they then drift further away.
“What we have determined is that the majority of stars are spinning fast precisely because they’re in a binary system.”
Thanks to the most recent research and the model that resulted regarding binary evolution, scientists will be able to foresee what GRB-generating stars should appear like when it comes to temperature, luminosity, and the characteristics of their pair.