オリオン大星雲
The young stars in H II regions show evidence for containing planetary systems. The Hubble Space Telescope has revealed hundreds of "protoplanetary disks" (proplyds) in the Orion Nebula. At least half the young stars in the Orion Nebula appear to be surrounded by disks of gas and dust, thought to contain many times as much matter as would be needed to create a planetary system like the Solar System.