This Is What Will Happen To Our Sun After It Dies
“During the red giant phase, Mercury and Venus will certainly be engulfed by the Sun, while Earth may or may not, depending on certain processes that have yet to be fully worked out. The icy worlds beyond Neptune will likely melt and sublimate, and are unlikely to survive the death of our star.
Once the Sun’s outer layers are returned to the interstellar medium, all that remains will be a few charred corpses of worlds orbiting the white dwarf remnant of our Sun. The core, largely composed of carbon and oxygen, will total about 50% the mass of our present Sun, but will only be approximately the physical size of Earth.”
Looking forward in time, the death of our Sun is easy to envision, as we’ve seen Sun-like stars in their dying phases and immediately afterwards plenty of times. But what happens after that, in the far future? Will our Sun’s corpse remain a white dwarf forever? Will it simply cool down, radiating heat away? Or will something exciting happen?
Maybe we’ll get ejected from the galaxy. Maybe we’ll get devoured by a black hole. Maybe we’ll merge with another object, or experience an interaction that forever changes us from what we were. Maybe we’ll even experience a cataclysm that destroys our stellar corpse entirely!
Although the possibilities are fascinating, there’s an overwhelming statistical likelihood that points to one particular outcome. What is it? Find out today!
Ask Ethan: Why Do Stars Come In Different Sizes?
“Why can suns grow to… many different sizes? That is, ranging from somewhat larger [than] Jupiter up to suns exceeding Jupiter’s orbit?”
“Bigger mass makes a bigger star,” you might be inclined to say. The smallest stars in size should be small because they have the least amount of material in them, while the largest ones of all are the largest because they’ve got the most material to make stars out of. And that’s a tempting explanation, but it doesn’t account for either the smallest stars or the largest ones in the Universe. As it turns out, neutron stars and white dwarfs are almost all larger in mass than our own Sun is, and yet the Sun is hundreds or even many thousands of times larger than they are. The most massive star known is only 30 times the physical size of our Sun, while the largest star of all is nearly 2,000 times our Sun’s size. As it turns out, there’s much, much more at play than mass alone.
Why do stars really come in different sizes, and how do we even know how big a star is at all? Find out on this week’s Ask Ethan!
When Will The First Star Go Dark?
“I’m sorry to disappoint you, but there aren’t any black dwarfs around today. The Universe is simply far too young for it. In fact, the coolest white dwarfs have, to the best of our estimates, lost less than 0.2% of their total heat since the very first ones were created in this Universe. For a white dwarf created at 20,000 K, that means its temperature is still at least 19,960 K, telling us we’ve got a terribly long way to go, if we’re waiting for a true dark star.”
Stars live for a variety of ages, from just a million or two years for some to tens of trillions of years for others. But even after a star has run out of its fuel and died, its stellar corpse continues to shine on. Neutron stars and white dwarfs are both extremely massive, but very small in volume compared to a star. As a result, they cool very slowly, so slow that a single one has not yet gone dark in all the Universe. So how long will it take, and who will get there first: neutron stars or white dwarfs? Believe it or not, there’s still enough uncertainty about how neutron stars cool, mostly due to uncertainties in neutrino physics, that we think we know the answer to be white dwarfs – and 10^14 or 10^15 years – but we’re not entirely sure!
Come find out what we know about finding the first truly dark star in the Universe today.