I have a basic understanding of how gaseous bodies behave according to their mass:
- "Low mass" bodies are gas giants (or brown dwarfs),
- Beyond a certain mass, hydrogen fusion starts, making a star,
- More massive bodies burn shinier and faster,
- Beyond a certain mass, even the thermonuclear fusion can't prevent the collapse into a black hole.
I don't know if there is a stage between the last two, only depending on initial mass (not talking about star evolution, when they burn their fuel)
But, how would a very massive rocky body behave?
I guess that a rocky body of a solar mass wouldn't become a star, because its heavy compounds couldn't fusion at such pressures,
I also guess that at some mass (not necessarily the same for the stars), it would collapse into a black hole.
Are these guesses true? Would there be an intermediary stage between the two (a star like form, or otherwise)? Or, would such a body be somehow impossible/unstable?