(S (S (BASENP (NNS Scientists)) (VP (VBP say) (SBAR (IN that) (S (BASENP (NNS bursts)) (VP (VBP signal) (NP (BASENP (DT the) (NN beginning)) (PP (IN of) (NP (BASENP (DT a) (NN star) (POS 's)) (NN death))))))))) (PERIOD .))