( ( ( The sources ) ( in ( this category ) ) ) ( ( are ( ( ( ( ( neutron stars ) or ) ( black holes ) ) ( - ( ( ( the results ) ( of ( a ( supernova explosion ) ) ) ) - ) ) ) ( which ( orbit ( a ( normal star ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NNS sources)) (PP (IN in) (NP (DT this) (NN category)))) (VP (VBP are) (NP (NP (NP (NN neutron) (NNS stars)) (CC or) (NP (JJ black) (NNS holes))) (PRN (: -) (NP (NP (DT the) (NNS results)) (PP (IN of) (NP (DT a) (NN supernova) (NN explosion)))) (: -)) (SBAR (WHNP (WDT which)) (S (VP (VB orbit) (NP (DT a) (JJ normal) (NN star))))))) (. .)))
The sources in this category are neutron stars or black holes -the results of a supernova explosion- which orbit a normal star.
(ROOT (S (NP (NN Neutron) (NNS stars)) (VP (VBP are) (NP (NP (DT the) (NNS corpses)) (PP (IN of) (NP (ADJP (VBN left) (RP over)) (NN supernova) (NNS explosions))))) (. .)))