Nebula Dust

Although these nebulae appear differently at optical wavelengths, they are all bright sources of emission at infrared wavelengths. This emission comes chiefly from the dust within the nebulae.
Planetary nebulae
Planetary nebulae are nebulae that form from the gaseous shells that are ejected from low-mass asymptotic giant branch stars when they transform into white dwarfs. These nebulae are emission nebulae with spectral emission that is similar to the emission nebulae found in star formation regions. Technically, they are an HII region because most hydrogen will be ionized. However, planetary nebulae are denser and more compact than the emission nebulae in star formation regions. Planetary nebulae are so called because the first astronomers who observed these objects thought the nebulae resembled the disks of planets, although they are not related to planets. Our sun is believed to become one of these 12 billion years after the suns formation.