How is a star formed? This is probably such a boring question but it's something thar just hit me. Also, when every star dies, does it always create a black hole?
I’ll try to keep the star formation part short because... it’s a lot? :’D It’s not a boring question at all sndbfhjnf
Basically, stars are formed when a lot of cold interstellar gas - of which there is a lot, both inside and outside of galaxies - is in one place. When there’s enough gas in one place, it starts to develop gravitation! (Fun fact: every object with a mass has a gravitational force. Even you. It’s just too small to make a difference in the grand scheme of things lol)
You can guess what happens next: some kind of “core” starts forming. When the gravitational force becomes big enough, lots of atoms & molecules from the gas get added to the nucleus until the core stabilizes itself. But the core isn’t made up of all the molecules there were in the gas cloud, so a lot of the surrounding molecules keep falling into the core, which creates shock waves that heat the core up! (alongside with some other stuff like gravitational energy getting turned into heat energy).
Once the core is hot enough to separate H2-molecules into 2 H-atoms, the heating process stops. But splitting up molecules means that the core doesn’t have enough energy left to uphold its structure, so it collapses again until it’s finally stable.
When that happens, there is a small but very hot core made up of solely H-molecules. That’s a protostar! This protostar radiates light and heat and a bunch of other stuff, that gets absorbed and/or reflected by the rest of the molecule cloud around it. So it keeps heating up further and keeps gaining mass from the cloud until it’s big enough to be classified as a star :D By then, it’s doing what a star does best: fusing H-atoms to gain energy by creating heavier elements.
That entire process takes millions of years.
(btw, around the star some kind of gas disk starts forming because the star has to uphold its “angular momentum” - it rotates. this is where planets get formed later!)
Nope, not every dying star turns into a black hole. Only the ones that started out as veeery big and heavy :’D Our sun, for example, will become a “white dwarf” - a super dense, hot core that doesn’t fuse anything anymore, just keeps glowing less and less until it disappears. White dwarfs are about as big as Earth, so really small!^^