This question was triggered by a discussion regarding the computer game Elite: Dangerous, where spaceships routinely operate in close proximity to stars (two or three light seconds away), at which point heat becomes an issue. Someone claimed that you would hardly feel any heating effect since there is so little matter around, indeed that you couldn't really tell if you are inside a star or not. I found that very dubious.
So let us assume we have spaceships and could fly around the solar system at will. Our ships have a certain degree of ruggedness to them, so people might get adventurous. What would it actually be like to approach, or even enter, a star?
We know that the corona is hot, hotter even than the surface. But it is also much less dense.
Q1: Would there actually be enough matter in the corona to make our ship heat up, or would we be able to ignore the very hot but few particles around us? What of the photosphere, or the upper convection zone -- those are still much less dense than earth's atmosphere at sea level. How much would the heating affect us?
Assuming we could pass through the corona, we would reach the photosphere, the point at which the (mostly hydrogen) body of the sun becomes opaque.
Q2: Does this opaqueness only apply to a certain layer (i.e. would we be able to "see" again once we go below the photosphere), or are all lower layers of the sun opaque? How opaque is that -- would we be able to see a couple of meters, some kilometers, or nothing at all?
Q2b: Would the matter directly in front of our cockpit window be bright, or dark?