Assertion: nebula's material | /r/HasProperty | composed
Facets:
value: from helium
type: OTHER
value: from hydrogen
type: OTHER
value: from other heavier elements
type: OTHER
Source sentences:
text: Material from these layers builds up the central and more conspicuous part of the planetary nebula, and is composed not only from hydrogen and helium, but also from other heavier elements produced in the stellar interior during its life of billions of years.