69864
Theoretical studies indicate that most supernovae are triggered by one of two basic mechanisms : the sudden re-ignition of nuclear fusion in a degenerate star such as a white dwarf , or the sudden gravitational collapse of a massive star 's core .
 degenerate star
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 degenerate star