Assertion: nebula's star | /r/CapableOf | start to shed its outer layers
Facets:
Source sentences:
text: Other types of nebulae include emission nebulae, which are clouds of ionized gas emitting light of various colors; dark nebulae, which are clouds of gas so dense that background light is blocked; and protoplanetary nebulae, which occur when a star starts to shed its outer layers before becoming a planetary nebula.
text: Planetary nebulae are formed when Sun-like stars in their final stages of life run out of fuel and start shedding off their outer layers and releasing gas at high speeds.