Analysis of information sources in references of the Wikipedia article "Nebulosa planetária" in Portuguese language version.
A planetary nebula (PN) is an expanding ionized circumstellar cloud that was ejected during the asymptotic giant branch (AGB) phase of the stellar progenitor. The nebula is ionized by the hot central star.
A planetary nebula (PN) is an expanding ionized circumstellar cloud that was ejected during the asymptotic giant branch (AGB) phase of the stellar progenitor. The nebula is ionized by the hot central star.