Brown dwarf

Yes.

How is a brown dwarf different from our sun? And why is it such a useful place for studying distant weather?

So, yeah, brown dwarfs are what we term substellar objects.

That means they're not quite a star.

They're also not quite a planet.

Whereas a planet doesn't glow of its own energy from fusion.

It can glow from heat and whatnot, but it's not fusing together atoms to produce light.

And these brown dwarfs fit right in the middle.

20 light-years away, there's an object called SIMP 0136.

It's a brown dwarf, too heavy to be a planet in the ordinary sense, too light to have ever ignited hydrogen fusion and become a star.

It sits right on the boundary, and it has no host star at all.

It's just drifting.

Outside of our solar system, but well within our galaxy.

So what we call brown dwarfs are worlds that formed like stars, but they don't shine like stars because they're not massive enough, so they cool down throughout their lifetimes, and they develop atmospheres very similar to planets that we have in our solar system.

And they're easier to study than exoplanets because they're not hidden beside these bright stars, 'cause planets form around stars, but these brown dwarfs don't.

So we use them as laboratories to study weather on these worlds outside of our solar system and understand what drives the weather and what shapes their atmospheres.

How are you looking at them? How do you spot them?

So we can see this change in light, and we can try and relate it back to the weather on these objects.

How do you know that's actually the "weather" in inverted commas that you're seeing? That tho- those changes in light and dark and, and therefore the density of what's around the object, how do you know that's the weather and clouds and so on?

So like I mentioned, brown dwarfs form like stars, so they create all of this mass, and then that leaves them kind of in this hot state where they emit energy, and this energy is emitted in the form of heat.

The first exoplanets confirmed by science were therefore worlds around a stellar corpse.

Brown dwarfs are failed stars with weather stranger than any planet.

These objects form like stars from collapsing clouds of gas, but they never gain enough mass to sustain stable hydrogen fusion.

That leaves them in an in-between category.

Rock and metal, the materials of crusts and cores, become part of the sky.

A brown dwarf may never become a star, but its atmosphere can still perform extraordinary experiments in alien weather.

Free-floating brown dwarfs glow faintly as they cool through time.

Without a parent star to illuminate them, isolated brown dwarfs are difficult to find.

And massive storms rage across its atmosphere, and deep inside, its core is still glowing red from the heat of its formation.

And because it's so young, only a few million years old, it's still radiating leftover heat, almost like a failed star that never cooled down.

But gas giants and stars are separated by one critical line, mass.

If an object reaches about 13 times the mass of Jupiter, the pressure in its core becomes strong enough to trigger nuclear fusion, and it officially becomes a brown dwarf star.

No more fuel, no more growth.

So now it's kind of just stuck, just drifting through space, glowing faintly in infrared, too big to be a planet, too small to be a star.

That's what scientists call a sub-brown dwarf, or more dramatically, a failed star.

And if you could somehow fly into it, you'd sink through thick, crushing gas, deeper and deeper as pressure builds to unimaginable levels.