HST discovered that about half of the young stars in the Orion nebula have disks around them.
Dust emits in the infrared.
Stars that emit extra infrared radiation in the wavelength that dust emits are believed to have disks around them. These are stars that may have a planetary system already formed. Stars with dense gas and dust disks have been detected in the radio. These planetary systems may still be forming. If the Solar Nebula theory is correct, the planets of the Solar System formed from the dust and gas disk that surrounded the early Sun.