A protoplanetary disk (or proplyd) is a rotating disk of dense gas surrounding a young newly formed star, a
T Tauri star or
Herbig star. The protoplanetary disk may be considered an
accretion disk because gaseous material may be falling from the inner edge of the disk onto the surface of the star, but this process should not be confused with the accretion process thought to build up the planets themselves.
See more at Wikipedia.org...