Assertion: nebula's star | /r/HasProperty | central
Facets:
Source sentences:
text: Like other planetary nebulae, the Dumbbell Nebula is formed by a central star that illuminates its expanding shell of gas, expelled by the star after it had used up all of its nuclear fuel.
text: Although this nebula has long been known, its true nature as a planetary nebula was only confirmed comparatively recently when it was discovered that its central star is a long period, double degenerate binary system.
text: A definite relation exists between the character of a nucleus and the type of its nebula: small, bright planetary nebulas have central stars of the Wolf-Rayet type; ring-like nebulas have central stars with a continuous spectrum; and large, irregular nebulas have ordinary stars of spectral class O as nuclei.