<s>[INST] Can a star cool down enough and become a giant planet? [/INST] Yes, a star can turn into a planet, but this transformation only happens for a very particular type of star known as a brown dwarf. Some scientists do not consider brown dwarfs to be true stars because they do not have enough mass to ignite the nuclear fusion of ordinary hydrogen.</s>\ <s>[INST] How is a brown dwarf formed? What makes it different from other dwarf stars? [/INST] They are formed in the same way as stars and planets, namely by the gravitational collapse of a gas cloud. 

Unlike white dwarfs, brown dwarfs are protostars and not 'dead stars'. This makes them more like T Tauri stars, which are pre-main sequence stars and also have unstable burning phases for hydrogen.</s>