( ( To ( define ( the ( absolute magnitude ) ) ) ) ( , ( ( put ( stars ( at ( a ( fixed distance ) ) ) ) ) ( , ( specifically ( , ( 10 ( parsecs . ) ) ) ) ) ) ) )
(ROOT (S (S (VP (TO To) (VP (VB define) (NP (DT the) (JJ absolute) (NN magnitude))))) (, ,) (S (VP (VB put) (NP (NP (NNS stars)) (PP (IN at) (NP (DT a) (VBN fixed) (NN distance)))))) (, ,) (ADVP (RB specifically)) (, ,) (NP (CD 10)) (VP (VBZ parsecs)) (. .)))
To define the absolute magnitude, put stars at a fixed distance, specifically, 10 parsecs.
(ROOT (S (NP (NNP Distance)) (VP (VBZ is) (VP (VBN defined) (PP (IN as) (NP (NP (DT the) (NN magnitude) (CC or) (NN size)) (PP (IN of) (NP (NP (NN displacement)) (PP (IN between) (NP (CD two) (NNS positions))))))))) (. .)))