Can you buy a planet or a star?

Excuse me, but could you elaborate on the possibility of purchasing a planet or a star? It seems like an intriguing concept, but I'm not entirely sure if it's even feasible. Is there any precedent for such transactions? Are there any laws or regulations in place that govern the ownership of celestial bodies? And if it is possible, how would one even go about acquiring a planet or a star? It would be great if you could provide some insight into this matter.