Main Question or Discussion Point
How can we decide which process is causing light to bend near the surface of a star? Gravity is said to cause light to bend or deflect as it passes near the huge mass of a star. But matter in the troposphere of a star should also cause light to bend or deflect as it passes through the troposphere of the star because there should be a lot of matter (electrons, protons, H and He) in the troposphere of a star. How do I decide which is the dominant effect?