In the life cycle of an average star, what follows the main sequence star stage?

After a star has spent a significant period of time in the main sequence stage, it will eventually exhaust the hydrogen fuel in its core. For stars that are of average mass, such as our Sun, the next stage in their life cycle is to expand into a red giant. This expansion is a result of the core contracting and heating up, which allows the outer layers to expand and cool, giving the star a reddish appearance.

Following the red giant phase, the star sheds its outer layers in a process that creates a planetary nebula. This expelled gas forms a beautiful shell of ionized gas surrounding the remaining core of the star. The core that remains after this shedding is what will eventually cool and shrink into a white dwarf. The planetary nebula marks the transitional process leading to the formation of this white dwarf.

In contrast, red supergiants and supernovae are phases associated with more massive stars, which undergo a different evolutionary path. After the red supergiant phase, these large stars can explode in a supernova, but that is not applicable in the average star scenario described. Thus, in the context of an average star’s life cycle, the correct answer specifically refers to the formation of a planetary nebula as the next step following the