What Will Stars Look Like in the Distant Future?

I'm talking billions, trillions of years, maybe even more. It's a somewhat sobering reality that nearly all of the stars that will be born during the lifetime of the universe have already been made. Now, stars as we know them will continue being made for billions of years, far beyond the life of humanity. But in the far-flung future, different types of stars will begin to pop up, stars that haven't had enough time to develop yet. Here's a list of four of those hypothetical future stars:

This won't do you much good here.

1. Blue dwarf. They're simple enough, they're the final phase of evolution of red dwarfs, the smallest type of star. Instead of expanding into a red giant like the Sun will when it starts fusing helium, they'll get smaller and much hotter, turning blue. However, their ultimate fate will be the same, eventually turning into white dwarfs.

2. Black dwarf. Hey, speaking of white dwarfs, this is what will happen to those after billions of years and they've cooled off. To call it a star is a bit generous, a black dwarf will be a planet-sized lump of super-dense matter generating little, if any, light.

3. Frozen star. Here's where things start to get strange. Eventually, the universe will run low on hydrogen and helium, but stars of a sort will continue to form, fusing paltry scraps of hydrogen in among icy clouds. These stars would struggle to get past the melting point of water, and would resemble giant brown dwarfs rather than actual stars.

4. Iron star. Now we're into real hypothetical territory here. As the universe slowly expands to infinity, undergoing heat death, there will be a lot of iron floating around. Iron is both extremely stable and if you know your fusion, you'll know that once you start fusing iron, more energy is used to make the reaction than is put out. That's what causes supernovae. However, and providing protons don't decay, when a bunch of iron clumps together to form a body, quantum shenanigans will cause an ignition of sorts, splitting the atoms and forming an iron star.