nov ae ▁or ▁super nov as ) ▁results ▁from ▁the ▁rapid ▁collapse ▁and ▁violent ▁explos ion ▁of ▁a ▁massive ▁star . ▁A ▁star ▁must ▁have ▁at ▁least ▁ 8 ▁times , ▁but ▁no ▁more ▁than ▁ 4 0 ▁to ▁ 5 0 ▁times , ▁the ▁mass ▁of ▁the ▁Sun ▁() ▁to ▁under go ▁this ▁type ▁of ▁explos ion . ▁Type   II ▁super nov ae ▁are ▁distinguished ▁from ▁other ▁types ▁of ▁super nov ae ▁by ▁the ▁presence ▁of ▁hydro gen ▁in ▁their ▁spect ra . ▁They ▁are ▁usually ▁observed ▁in ▁the ▁spir al ▁arms ▁of ▁galaxies ▁and ▁in ▁H   II ▁regions , ▁but ▁not ▁in ▁elli pt ical ▁galaxies ; ▁those ▁are ▁generally ▁composed ▁of ▁older ▁low - mass ▁stars , ▁with ▁few ▁of ▁the ▁young ▁highly ▁massive ▁stars ▁necessary ▁to ▁cause ▁a ▁super n ova . ▁ ▁Stars ▁generate ▁energy ▁by ▁the ▁nuclear ▁fusion ▁of ▁elements . ▁Un like ▁the ▁Sun , ▁massive ▁stars ▁possess ▁the ▁mass ▁needed ▁to ▁f use ▁elements ▁that ▁have ▁an ▁atomic ▁mass ▁greater ▁than ▁hydro gen ▁and ▁hel ium , ▁al beit ▁at ▁increasing ly ▁higher ▁temper atures ▁and ▁press ures , ▁causing ▁increasing ly ▁shorter ▁stell ar ▁life ▁sp ans . ▁The ▁deg ener acy ▁pressure ▁of ▁electrons ▁and ▁the ▁energy ▁generated ▁by ▁these ▁fusion ▁re actions ▁are ▁sufficient ▁to ▁counter ▁the ▁force ▁of ▁gravity ▁and ▁prevent ▁the ▁star ▁from ▁col laps ing , ▁maintain ing ▁stell ar ▁equilibrium . ▁The ▁star ▁f uses ▁increasing ly ▁higher ▁mass ▁elements , ▁starting ▁with ▁hydro gen ▁and