( ( Depending ( upon ( various factors ) ) ) ( , ( ( the ( carbon star ) ) ( ( could ( ( ( become ( a ( white dwarf ) ) ) or ) ( ( go on ) ( to ( burn silicon ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (VBG Depending) (PP (IN upon) (NP (JJ various) (NNS factors)))) (, ,) (NP (DT the) (NN carbon) (NN star)) (VP (MD could) (VP (VP (VB become) (NP (DT a) (JJ white) (NN dwarf))) (CC or) (VP (VB go) (PRT (RP on)) (S (VP (TO to) (VP (VB burn) (NP (NN silicon)))))))) (. .)))
Depending upon various factors, the carbon star could become a white dwarf or go on to burn silicon.
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (DT the) (NNP helium)) (VP (VBZ is) (VP (VBN gone))))) (, ,) (NP (DT the) (NNS stars)) (VP (VBP become) (NP (JJ white) (NNS dwarfs))) (. .)))