After a smaller star runs out of hydrogen it begins to become a :

Stars Like the Sun. When the core runs out of hydrogen fuel, it will contract under the weight of gravity. ... The upper layers will expand and eject material that will collect around the dying star to form a planetary nebula. Finally, the core will cool into a white dwarf and then eventually into a black dwarf.

its temperature is increasing. this causes molecular vibrations to increase.

b) the inside picture would look at a very high temperature in a very low ph