# Stars - A Synopsis Stars are big, hot spheres of material which generate their own energy by forcing small, light hydrogen nuclei together. (More Info [[Nuclear & Quantum Contents (Nuclear & Quantum)]]) # How are they formed? Stars come together through the collapse of large molecular clouds - or "nebulae", if you're a traditionalist. Essentially, material in the outer layer of the nebula collapses inward onto the centre, increasing the density of the middle. %%diagrams pls %% This increased density does not strictly have a shape to it (although hydrostatic equilibrium will bring it to a sphere over time), creating what's called a **Protostar**, a big, uneven lump of heavy material, generating its own heat through the frictional forces of the sheer amount of material being dumped onto it. The material around this large, central clump experiences **polar flattening** and turns into a relatively flat **accretion disc**. Material in this accretion disc can slowly come together through collisions, first creating **planetesimals** then **planets**. A star actually undergoes different types of nuclear fusion. Low-mass stars undergo proton-proton chaining, where hydrogen nuclei come together in a series of collisions to create heavier deuterium then helium nuclei. However, this intermediary stage, with deuterium fusion, can actually occur at lower pressures and temperatures than the minimum threshold for hydrogen nuclei fusion. Lithium abundances in protostars (for business reasons now proto-stellar objects) can also lead to fusion, as lithium can fuse with deuterium atoms to form helium nuclei too! However, deuterium stocks are often much lower than hydrogen, so this phase only lasts for a certain amount of time. This means that stars which reach the threshold for # Our Sun - A (Shallow) Dive # Binary Star Systems (TBA) ![[Pasted image 20240206091144.png]] # What's Next? You're done! We'll move on to more specific topics now, maths now included! To check out failed stars, go here: [[Brown Dwarfs (Astro)]] To check out low-mass stars, go here: [[Red Dwarves - A Crash Course (Astro)]] To check out hot sun-like stars near you, go here: [[Our Sun - A Garden Variety Star (Astro)]] To check out high-mass stars, go here: 1. [[Blue Giants (Early B-O Type) (Astro)]] 2. [[Blue Dwarves (Late B) (Astro)]] For more about space and sciences, be sure to check the links here: 1. [[Up In The Stars]] --> Navigate anywhere within my Astronomy Subpage 2. [[An Astrophysics Landing Page]] --> Navigate anywhere astrophysics! For more information about nuclear fusion, go here: [[Fission and Fusion (Nuclear & Quantum)]]