Once a star has begun sustained nuclear fusion at its core, its stellar winds start to clear out the surrounding dust, gas, and other debris. Some of that debris, however, settles into a thin, swirling disk that orbits around the newly born star. This structure is referred to as a protoplanetary disk. It is so named because that is where the raw materials for the planets in that star system have gathered, and where those planets themselves will likely be born.