( ( ( ( ( ( The gas ) ( ( ( ( ( is ( highly enriched ) ) ( by ( heavy elements ) ) ) , ) ( with ( ( four ( times more ) ) ( ( calcium and ) iron ) ) ) ) ( than ( the Sun ) ) ) ) , ) and ) ( that ( ( confirms ( earlier suspicions ) ) ( that ( ( Sagittarius ( A East ) ) ( is ( ( ( most likely ) ( a remnant ) ) ( of ( a ( supernova explosion ) ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (DT The) (NN gas)) (VP (VBZ is) (ADJP (RB highly) (JJ enriched)) (PP (IN by) (NP (JJ heavy) (NNS elements))) (, ,) (PP (IN with) (NP (QP (CD four) (NNS times) (RBR more)) (NN calcium) (CC and) (NN iron))) (PP (IN than) (NP (DT the) (NNP Sun))))) (, ,) (CC and) (S (NP (DT that)) (VP (VBZ confirms) (NP (JJR earlier) (NNS suspicions)) (SBAR (IN that) (S (NP (NNP Sagittarius) (NNP A) (NNP East)) (VP (VBZ is) (NP (NP (ADJP (RBS most) (JJ likely)) (DT a) (NN remnant)) (PP (IN of) (NP (DT a) (NN supernova) (NN explosion))))))))) (. .)))
The gas is highly enriched by heavy elements, with four times more calcium and iron than the Sun, and that confirms earlier suspicions that Sagittarius A East is most likely a remnant of a supernova explosion.
(ROOT (S (NP (NNS Supernovas)) (VP (VBP are) (ADJP (ADJP (NP (NP (DT the) (NN source)) (PP (IN of) (NP (NNS elements)))) (JJR heavier)) (PP (IN than) (NP (NN iron))))) (. .)))