What are protoplanetary objects?
Protoplanetary objects are are clumps of material which will ultimately form a planet.
Stars are born in a clouds of dust and gas. The star consumes almost all of the material. If there is enough solid material orbiting around a new star is forms a protoplanetary disc. The material in the disc starts to clump together into larger and larger clumps. These are protoplanetary objects or bodies. Ultimately all of the protoplanetary bodies in a particular orbit will combine to form a planet. The process can take millions of years.