4 ms·
maybe think of it as "ash" the newly fused element is more massive than the ones it came from and sinks to the bottom (core) When enough "ash" is accumulated
by tejtm 5y ago
maybe think of it as "ash"
the newly fused element is more massive than the ones it came from
and sinks to the bottom (core)
When enough "ash" is accumulated (and the star is still big enough)
the previous ash begins fusing into some new heavier "ash"
rinse and repeat until you get to iron "ash" but no further.
the reason is; every fusion lighter than iron is exothermic
two atoms fuse into something bigger than either,
but smaller than both,
plus releasing some energy (yay).
when you get to fusing iron you need a ball about 20 miles in diameter
and fusing does not give up energy,
fusing iron needs to take energy from its environment.
good thing it is not in the middle of a star big enough to grow a twenty mile ball of iron.
and that kids is where supernova come from
once iron fusion starts it all goes in moments collapsing the core
and the star above where the core was "falls" into that space
gravitationally propelled with enough speed that when it hits the opposite side (falling just as fast in the other direction) everything fuses into "whatever"
that is about as exciting as it gets in this universe
- jcims 5y agoI do get that part, but I like your description. The thing that I was interested in is whether or not a helium atom in the Earth‘s atmosphere has a way to be sucked into the fusing layer at some point. It just seems from everything that I’ve learned over the years that there’s a net outflow of that would likely keep the little atom some distance away even if it left Earths gravity well.
- tejtm 5y agoI see, if you are not already part of the "in crowd" below the photo-sphere can you get past the solar wind bouncers. I don't know, but think it would be tough for a lone atom.
- justin66 5y ago> The thing that I was interested in is whether or not a helium atom in the Earth‘s atmosphere has a way to be sucked into the fusing layer at some point. It seems to me there are three possible fates for that helium, and two of them involve being used up by stellar fusion. The helium atoms get somehow pulled into the sun and so eventually get used up in a fusion reaction, the sun expands during its giant phase and envelops the Earth and the helium eventually gets used up in a fusion reaction, or the helium nuclei gets propelled out of the solar system with the solar wind. It'd actually be fun to estimate the odds of each option but I honestly have no idea. #3 feels like a long shot.
- semireg 5y agoAtom X by Leopold is a good short story similar to this idea of a single atom’s travels. https://www.audubon.org/magazine/may-june-1942/from-archives-aldo-leopolds-odyssey https://www.audubon.org/magazine/may-june-1942/from-archives...
- tejtm 5y agothanks for the short story