( ( The source ) ( ( has ( ( shown astronomers ) ( that ( ( rare events ) ( do ( ( ( exist , ) and ) ( that ( ( other ( supernova remnants ) ) ( could ( harbor ( ( the remains ) ( of ( ( other combinations ) ( of ( ( ( radioactive elements ) , ) ( which ( ( could further ) ( bolster ( supernova modeling ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN source)) (VP (VBZ has) (VP (VBN shown) (NP (NNS astronomers)) (SBAR (IN that) (S (NP (JJ rare) (NNS events)) (VP (VBP do) (SBAR (SBAR (S (VP (VBP exist)))) (, ,) (CC and) (SBAR (IN that) (S (NP (JJ other) (NN supernova) (NNS remnants)) (VP (MD could) (VP (VB harbor) (NP (NP (DT the) (NNS remains)) (PP (IN of) (NP (NP (JJ other) (NNS combinations)) (PP (IN of) (NP (NP (JJ radioactive) (NNS elements)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (MD could) (ADVP (RBR further)) (VP (VB bolster) (NP (NN supernova) (NN modeling))))))))))))))))))))) (. .)))
The source has shown astronomers that rare events do exist, and that other supernova remnants could harbor the remains of other combinations of radioactive elements, which could further bolster supernova modeling.
(ROOT (S (NP (NNS Supernovas)) (VP (VBP are) (ADJP (ADJP (NP (NP (DT the) (NN source)) (PP (IN of) (NP (NNS elements)))) (JJR heavier)) (PP (IN than) (NP (NN iron))))) (. .)))