system
Given the following post, respond as if you're commenting on Reddit:
human
Would it be possible to have a planet large enough that it is actually the center of the system and a smaller star revolves around it?

How small would a star have to be to revolve around Earth? Let's take our own Sun for example. And if you could not do it with our own, what temperature would the star have to be and/or what would it need to be composed of?
gpt
The smallest stars **by mass** are red dwarfs.  (There are actually brown dwarfs, star-like objects bigger than Jupiter, but not quite massive enough for sustained fusion.)  Either way, the smallest star is quite a bit larger than Earth.

The smallest star ever discovered is OGLE-TR-122b.  It's a little larger in diameter than Jupiter, but 100 times more massive.  Because it's much more massive than Earth, it could not orbit Earth.

Also, technically, orbital systems, like binary stars, Earth/Moon, etc., orbit the common center of mass.

The upshot is that it may be possible to have a binary system consisting of a planet slightly larger than Jupiter, but not quite big enough for fusion, and a red/brown dwarf.  They would orbit their common center of mass, but the dwarf star would still have to have roughly 99% of the mass, despite the two bodies having comparable radii.

**EDIT: For clarification, all uses of the terms "size," "large," "small," etc. in this thread are referring to mass.  Volume is mostly meaningless in the context of gravitational attraction.**

Edit 2: "Star-like objects," as brown dwarfs are technically not stars.