1. Gravity: Nebulae are vast clouds of gas and dust. Gravity pulls these particles together, causing the cloud to collapse. As the cloud collapses, it becomes denser and hotter.
2. Nuclear Fusion: As the core of the collapsing nebula reaches a certain temperature and pressure, nuclear fusion begins. This is a process where hydrogen atoms fuse together to form helium, releasing tremendous amounts of energy in the form of light and heat. This energy output creates outward pressure that balances the inward pull of gravity, stabilizing the star and allowing it to shine.
Let me know if you want a more detailed explanation of either of these processes!
