( ( ( Supernovae and ) neutron ) ( stars . ) )
(ROOT (S (NP (NN Supernovae) (CC and) (NN neutron)) (VP (VBZ stars)) (. .)))
Supernovae and neutron stars.
(ROOT (S (NP (NP (DT The) (NN core)) (PP (IN of) (NP (DT a) (NN star)))) (VP (VBZ collapses) (PP (IN during) (NP (DT a) (NN supernova))) (, ,) (S (VP (VBG forming) (NP (DT a) (NN neutron) (NN star))))) (. .)))