A protoplanetary nebula or preplanetary nebula (Sahai, Sánchez Contreras & Morris 2005) (PPN, plural PPNe) is an astronomical object which is at the short-lived episode during a star's rapid evolution between the late asymptotic giant branch (LAGB) phase and the subsequent planetary nebula (PN) phase.

What is an example of a stellar nebula?

The Orion Nebula is an emission nebula and star-forming region. It is the most active star-forming region in our Galaxy, and can easily be observed up-close with a small telescope. The Orion Nebula is a perfect example of a star-forming region or “stellar nursery”.

What type of nebula is a planetary nebula?

A planetary nebula (PN, plural PNe), is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives. The term "planetary nebula" is a misnomer because they are unrelated to planets.