Assertion: nebula's star | /r/HasProperty | rare
Facets:
value: very
type: DEGREE
Source sentences:
text: Interestingly, when even heavier stars collapse to black holes there is little energy release, hence they are not observable as supernovae, but such massive stars are very rare.
text: In general, that’s always true: Massive, luminous stars are rare, and lower mass, cooler stars more common.