A protoplanetary nebula or preplanetary nebula[1] (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)[a] phase and the subsequent planetary nebula (PN) phase. A PPN emits strongly in infrared radiation, and is a kind of reflection nebula. It is the second-from-the-last high-luminosity evolution phase in the life cycle of intermediate-mass stars (1–8 M☉).[2]: 469
- ^ Sahai, Raghvendra; Sánchez Contreras, Carmen; Morris, Mark (2005). "A Starfish Preplanetary Nebula: IRAS 19024+0044" (PDF). The Astrophysical Journal. 620 (2): 948–960. Bibcode:2005ApJ...620..948S. doi:10.1086/426469.
- ^ Kastner, J. H. (2005), "Near-death Transformation: Mass Ejection in Planetary Nebulae and Protoplanetary Nebulae", American Astronomical Society Meeting 206, #28.04; Bulletin of the American Astronomical Society, 37, Bibcode:2005AAS...206.2804K