energy, accelerating the collapse.
The events in the core reverberate throughout the star. The core was supporting the outer layers of the star, and when the core collapses, for them it’s a real-life Wile E. Coyote moment: just as when the cartoon character suddenly realizes he is no longer over solid ground and starts to fall, the gas from the star’s outer layers suddenly finds itself hovering over a vacuum and comes crashing down. The incredible gravity of the core accelerates the gas hugely, and it slams into the compressed core at a significant fraction of the speed of light.
This creates a huge rebound effect that reverses the direction of the inbound gas and starts to blow it back out. This rebound, as vast as it is, is amazingly not enough on its own to blow up the star; the explosion would stall, and the outer layers would begin to fall once again onto the core. But the star has one more surprise up its sleeve.
Even after the initial collapse, the core is still loaded with electrons. The tremendous heat and pressure from the collapse applies a huge force on these electrons, squeezing them together into the protons in the core. When this happens, the electrons plus protons create more neutrons. But they also create ghostly subatomic particles called neutrinos, and these are what spell disaster for the star. 23
Neutrinos are extremely tenuous particles, able to penetrate huge amounts of material without getting absorbed; to them even the densest material is nearly transparent. They blast out of the core, carrying away vast amounts of energy from the collapse. The energy they carry out is nothing short of staggering: it can equal the Sun’s entire lifetime output of energy ! In fact, the solid majority of the energy released in a supernova event is in the form of neutrinos; the visible light we see, blinding though it is, only adds up to a paltry 1 percent of the released energy.
The core generates neutrinos in unbelievably prodigious quantities: some 10 58 (that’s a 1 followed by 58 zeros, folks) of the particles scream out of the core over the course of about ten seconds. This is just around the same time that the outer layers of the star fall onto the core and begin their failed rebound. Just as the gigantic bounce fails, and all that material is about to fall back on the core, all those countless neutrinos slam into the gas.
Even though neutrinos tend to pass right through normal matter, the stellar gas is incredibly dense. Plus, there are just simply so many neutrinos that some fraction of them get absorbed no matter what—it’s like driving through a swarm of bugs in your car; no matter how much they avoid you, you’re still going to get some goo on your windshield.
Only a tiny fraction, maybe 1 percent, of the neutrinos get absorbed by the gas, but it’s still an epic event: the total energy dumped into the gas is huge.
This, this is what destroys the star.
It’s like setting off a bomb in a fireworks factory. The energy of a hundred billion billion Suns rips into the star’s outer layers, reversing their course, literally exploding them outward. Octillions of tons of doomed star tear outward at speeds of many thousands of miles per second. The event is so titanic that even the tiny fraction of it that is converted into light can be seen clear across the visible Universe.
And that’s just visible light. Other forms of light—X-rays, gamma rays, and ultraviolet light—also pour out of the newly formed supernova. As the shock wave of the explosion tears through the outer layers of the star, pressures and temperatures get so high that nuclear fusion can be triggered. In fact, elements heavier than iron can finally be created in this way, since the conditions in the blast wave are, incredibly, actually more violent than in the core of a star. Radioactive versions of elements like cobalt, aluminum, and titanium are created in the expanding debris, and they emit gamma rays when they decay. The
The events in the core reverberate throughout the star. The core was supporting the outer layers of the star, and when the core collapses, for them it’s a real-life Wile E. Coyote moment: just as when the cartoon character suddenly realizes he is no longer over solid ground and starts to fall, the gas from the star’s outer layers suddenly finds itself hovering over a vacuum and comes crashing down. The incredible gravity of the core accelerates the gas hugely, and it slams into the compressed core at a significant fraction of the speed of light.
This creates a huge rebound effect that reverses the direction of the inbound gas and starts to blow it back out. This rebound, as vast as it is, is amazingly not enough on its own to blow up the star; the explosion would stall, and the outer layers would begin to fall once again onto the core. But the star has one more surprise up its sleeve.
Even after the initial collapse, the core is still loaded with electrons. The tremendous heat and pressure from the collapse applies a huge force on these electrons, squeezing them together into the protons in the core. When this happens, the electrons plus protons create more neutrons. But they also create ghostly subatomic particles called neutrinos, and these are what spell disaster for the star. 23
Neutrinos are extremely tenuous particles, able to penetrate huge amounts of material without getting absorbed; to them even the densest material is nearly transparent. They blast out of the core, carrying away vast amounts of energy from the collapse. The energy they carry out is nothing short of staggering: it can equal the Sun’s entire lifetime output of energy ! In fact, the solid majority of the energy released in a supernova event is in the form of neutrinos; the visible light we see, blinding though it is, only adds up to a paltry 1 percent of the released energy.
The core generates neutrinos in unbelievably prodigious quantities: some 10 58 (that’s a 1 followed by 58 zeros, folks) of the particles scream out of the core over the course of about ten seconds. This is just around the same time that the outer layers of the star fall onto the core and begin their failed rebound. Just as the gigantic bounce fails, and all that material is about to fall back on the core, all those countless neutrinos slam into the gas.
Even though neutrinos tend to pass right through normal matter, the stellar gas is incredibly dense. Plus, there are just simply so many neutrinos that some fraction of them get absorbed no matter what—it’s like driving through a swarm of bugs in your car; no matter how much they avoid you, you’re still going to get some goo on your windshield.
Only a tiny fraction, maybe 1 percent, of the neutrinos get absorbed by the gas, but it’s still an epic event: the total energy dumped into the gas is huge.
This, this is what destroys the star.
It’s like setting off a bomb in a fireworks factory. The energy of a hundred billion billion Suns rips into the star’s outer layers, reversing their course, literally exploding them outward. Octillions of tons of doomed star tear outward at speeds of many thousands of miles per second. The event is so titanic that even the tiny fraction of it that is converted into light can be seen clear across the visible Universe.
And that’s just visible light. Other forms of light—X-rays, gamma rays, and ultraviolet light—also pour out of the newly formed supernova. As the shock wave of the explosion tears through the outer layers of the star, pressures and temperatures get so high that nuclear fusion can be triggered. In fact, elements heavier than iron can finally be created in this way, since the conditions in the blast wave are, incredibly, actually more violent than in the core of a star. Radioactive versions of elements like cobalt, aluminum, and titanium are created in the expanding debris, and they emit gamma rays when they decay. The
Similar Books
