How do stars form?

#Science - because science should blow your mind 🤯

How Do Stars Form?

A young scientist asked, "How does a nebula form stars?" What a fantastic question! In order to answer it, first I had to ask a lot more questions.

★ What actually IS a star?

A star is a giant ball of gas, hydrogen and helium, which is so massive that it can use its own gravitational pull like a net, drawing in more gas to feed itself and keep it burning. 98% of the matter in the universe is made up of hydrogen and helium, so there is plenty of star food out there just waiting to power new stars. As our young scientist knew already, baby stars are formed within nebulae, sometimes called star nurseries. (6)

★ So what is a nebula?

A nebula is a turbulent cloud of dust and gas. It's a little like the dusty pile of dog hair hiding behind my bedroom door. If I walk by quickly enough, the little pile swirls around, probably collecting more dust from the ground as I go. (Yes, I really need to vacuum). Now, you might be wondering, Where did the dust come from? (in the nebula, not in my bedroom) and Why is it turbulent if you're not walking past? And this is where things get really interesting. Sometimes a nebula is formed when an existing star dies. The supernova can cause an explosion of gas and dust strong enough to actually form a nebula! It's kind of amazing to think that a star could die, creating a nebula, that might then create more stars. It's like the ultimate recycling program. Other times, the nebula can't be traced back to a dead star, but matter has mass, and where there is mass, there is gravity not matter how strong or how infinitesimal. So a bit of dust pulls in a smaller bit of dust, and they clump together, making a bigger bit of dust, with a stronger gravitational pull, which can then collect more dust, and suddenly you have a giant clump of dog hair that needs to be vacuumed. I mean a nebula. But to create a star, you need turbulence within the nebula. (1,4,5)

★ Where does cosmic turbulence come from?

Have you ever flown in a plane? You're gliding along and it doesn't even really feel like you're moving, and then suddenly the captain says, "Buckle your seat belts, ladies and gentlemen. There's going to be turbulence. It's a pocket of air, of wind, usually related to weather. Turbulence in space is kind of the same thing. See, as stars suck in all that gas to keep them burning, they also spew stuff back out: radiation, which is basically an electromagnetic wave. And when a star spews out those highly charged negative particles, they have to go somewhere. They travel through space, bumping into each other, being pulled here and there by magnets, creating turbulence or Space wind. I mean you could say that the turbulence is essentially star farts. (I don't know if any self-respecting scientist would say that, but I'm a librarian, so I can probably get away with it for now.) So a star that has already been formed somewhere off in the universe is shooting off waves that travel through space creating turbulence inside of nebulae, stirring up the dust clouds to make new baby stars. It's kind of amazing, isn't it? (2)

★ So then what happens?

Eventually the nebulae gets so full and heavy with dust and gas that it collapses. Like how you might feel like you're going to explode if you eat way too much pasta--the nebula actually collapses in on itself in a sort explosion that heats up all of that matter until it's so hot and concentrated that it forms the central core of a protostar. That process of agitation within the nebula and eventual collapse may seem like it takes forever, about 100,000 years, but it's a drop in the bucket (one one-thousandth) on the journey to becoming a fully-fledged star. After about 100 million years (100,000,000) the star will finally be massive enough and hot enough that nuclear fusion starts--the process that allows the star to draw in more gas to sustain itself. (4,5)

★ Want to learn more? Check out these awesome resources that helped me write this little #Science article.

Jean M. Malone - July 2020