In the final moments of a massive star's life, its core begins to collapse under the influence of its own gravity, but the end is not always the same. The star may succeed in triggering a supernova explosion, or the collapse may continue until a black hole is formed.
A new study suggests that a hidden factor in this process may be neutrinos, which are extremely light subatomic particles that interact weakly with matter.
Why do neutrinos have such an effect?
Neutrinos are not insignificant particles in the death of stars. When the core of a massive star collapses, these particles carry about 99% of the energy released in the first few seconds, with only a very small percentage remaining, related to the kinetic energy of the explosion. Therefore, the way neutrinos move and interact with surrounding matter can influence the shock wave that forms during the collapse.
Neutrinos are characterized by having three main types or "flavors" associated with the electron, muon, and tau, and they can switch from one type to another in what is known as flavor conversion.
Stars between 16 and 30 solar masses surprise scientists
Researchers at the Niels Bohr Institute at the University of Copenhagen focused on the impact of neutrino transformation on stellar collapse models. Their calculations showed that stars with masses between 16 and 30 times that of the Sun were particularly sensitive to this factor; some stars that traditional models predicted would explode became, after the introduction of neutrino transformation, more likely to fail to explode and continue collapsing.
The result does not mean that neutrinos alone determine the fate of each star, as the explosion also depends on the properties of the star, the equation of state of nuclear matter, and the location of the transformation within the collapsing core.
From visible explosion to silent black hole
The significance of this finding lies in its potential to help scientists understand why there is a discrepancy between the number of supernovae we theoretically predict and the number we actually observe, as well as why some giant stars disappear without a clear explosion. This mechanism could also influence the final masses of neutron stars and the black holes left behind by collapsed stars.
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