Here's a breakdown:
1. Stellar Nebula: A giant cloud of gas and dust, primarily hydrogen and helium.
2. Star Formation: Gravity pulls the material in the nebula together, forming a denser core. As the core collapses, it heats up and eventually ignites nuclear fusion, marking the birth of a star.
3. Star: The star then enters the main sequence stage of its life, burning hydrogen into helium.
So, the duration of the stellar nebula stage depends on the size and density of the nebula, but it's generally millions to tens of millions of years before a star forms.
Think of it like this: A stellar nebula is like the ingredients for a cake, and the star is the cake itself. The ingredients don't stay as ingredients forever; they get transformed into the final product.
