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and nearly massless, neutrinos. At ordinary temperatures the process is incredibly rare that it probably hasn't happened within the visible universe anytime in the last 10 billion years, except perhaps in the core of these electroweak stars. But it could happen at the extreme temperatures and densities when a star begins to collapse into a black hole. The energy generated could halt the collapse, much as the energy generated by nuclear fusion prevents ordinary stars like the Sun from collapsing. In other words, an electroweak star is the possible next step before total collapse into a black hole. If the electroweak burning is efficient, it could consume enough mass to prevent what's left from ever becoming a black hole. Most of the energy eventually emitted from electroweak stars is in the form of neutrinos, which are hard to detect. A small fraction comes out as light, and this is where the electroweak star's signature will likely be found. Further study is required to understand such star better. And until then, it is hard to tell an electroweak star from the other varieties. There's time, however, to learn. The theorists have calculated that this phase of a star's life can last more than 10 million years - a long time for us, though just an instant in the life of a star. Figure 08-26b shows some of the massive stars in a nebula that could be electroweak stars.
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