Nebula

The term 'nebulae' originally described objects that appeared fuzzier than stars. Many of these were later identified as galaxies. Nebulae form in various ways, including from the remnants of exploding stars, fading smaller stars, or interstellar gas that coalesces under gravity.

What happens to smaller stars that leads to the formation of nebulae?

What role does interstellar gas play in the formation of nebulae?