If the sun does explode in the far future, what would make it explode?
In: Physics
The Sun won’t explode (aka supernovae), it’t not big enough for that, but here the process.
Stars like our sun have enough mass that the pressure at their center keep the material there. Meaning that the hydrogen they have in their core stay there and that they will only be able to consume the fuel they have in their core and not the rest in their outer layers.
Stars are in an equilibrium between two forces. The first is the gravity of their own mass trying to squeeze the star inward, and the second is the nuclear fusion that create an outward force. But when a star consume all their hydrogen in their core, the fusion inside stop, and without a outward force, gravity win. The core of the star is squeeze more and more and since it take time for the residual heat to get out of the core (it can take millions of years), the core of the star actually go up in temperature. This heat up the outer layers and like you probably know when something is heat up it become bigger, so that’s what the outer layer does. It grow to massive since and we call the star at that stage a Red Giant.
Now as the core of the star get compacted more and more by the gravity, the temperature rise enough that it can now fuse the helium in the core. Fusion start again, the outward force come back to fight back the graivty. The core get bigger absorbing the heat from the outer layer and the star is not a red Giant anymore, it goes back to looking more like it used to.
But eventually the helium get all consumed and the cycle continue. The core get compressed by the gravity, the star grew into a Red Giant, eventually the temperature in the core get high enough to fuse the next element. Each time the star get bigger and then smaller and then bigger against, it will launch material into space, slowly losing mass. Eventually, the mass of the star isn’t enough to keep the temperature in the core rising, so nothing happen anymore. Usually at this point all the outer layer was blasted away in space and what is left is just a naked core called a white dwarf. That’s what will happen to our sun.
If the star is massive enough, the cycle don’t stop. The core keep rising in temperature and fusion happen with bigger and bigger atoms until you reach Iron. Iron is important because it’s the first element that absorb more energy than it release when fusion happen. So now instead of nuclear explosion that create an outward force, the core start to suck all the heat from the star. Suddenly nothing is stopping gravity, no more fusion to keep the star stable. The star collapse under it’s own mass.
The only thing left that stop that collapse is a force that stop neutron from occupying the same space. The collapsing star smash into that force like a car would crash into a wall and this create the supernovea.
But star can be so massive that even the force that keep neutron from occupying the same space is not strong enough. The star collapse on itself into a black hole. Something so dense that even light can’t escape.
Latest Answers