What causes massive stars to expel their outer layers?

Question

Quizplus · Accepted Answer

Radiation pressure is the force exerted by photons on matter. When massive stars begin to run out of fuel in their core, they start to burn heavier elements in their outer layers. This process generates a lot of energy, which produces intense radiation pressure. This pressure pushes the outer layers of the star outwards, causing them to expand and eventually be expelled from the star. This is known as a stellar wind.

What Causes Massive Stars to Expel Their Outer Layers