( But ( ( if ( there ( ( ( ( is ( another star ) ) nearby ) , ) ( a ( binary companion ) ) ) ) ) ( , ( we ( ( can ( ( ( detected ( the ( black hole ) ) ) ( in directly ) ) ( by ( ( the effect ) ( it ( has ( on ( its companion ) ) ) ) ) ) ) ) . ) ) ) ) )
(ROOT (S (CC But) (SBAR (IN if) (S (NP (EX there)) (VP (VBZ is) (NP (DT another) (NN star)) (ADVP (RB nearby)) (, ,) (NP (DT a) (JJ binary) (NN companion))))) (, ,) (NP (PRP we)) (VP (MD can) (VP (VB detected) (NP (DT the) (JJ black) (NN hole)) (PP (IN in) (ADVP (RB directly))) (PP (IN by) (NP (NP (DT the) (NN effect)) (SBAR (S (NP (PRP it)) (VP (VBZ has) (VP (PP (IN on) (NP (PRP$ its) (NN companion))))))))))) (. .)))
But if there is another star nearby, a binary companion, we can detected the black hole in directly by the effect it has on its companion.
(ROOT (S (NP (NP (DT The) (JJ tidal) (NNS forces)) (PP (IN near) (NP (JJ black) (NNS holes)))) (VP (VBP are) (ADJP (RB so) (JJ great) (SBAR (S (NP (PRP they)) (VP (MD can) (ADVP (RB actually)) (VP (VB tear) (NP (NN matter)) (PP (IN from) (NP (DT a) (NN companion) (NN star))))))))) (. .)))