TYPE II SUPERNOVAE

HST press release

Type II supernovae are the most energetic stellar events seen in the Universe. They are the deaths of massive stars and involve the release of more than 10**53 ergs of energy. This is a tremendous amount of energy as the Sun will only produce 1.2 x 10**51 ergs of energy over the entire course of its lifetime. 99 % of the energy of a supernova comes out as neutrinos. Only 0.01 % of the energy actually goes into the visible fireworks seen on the sky. However, note that even this tiny amount of supernova energy allows supernova to stand out against even the background light of entire galaxies (see above)!

Supernovae are impressive beasts and are interesting simply from this standpoint. However, they are also quite interesting for other reasons:

• Supernovae produce most of the heavy elements (nucleosynthesis) that are found in the Universe
• Supernovae may trigger star formation (and at one time were even speculated to have triggered the formation of the Solar System).
• Supernovae are a major source of energy input into the ISM in general
• Supernovae might be used to determine the expansion rate of the Universe
• ....

Well, anyway, ho hum and let's go on

• Type I vs Type II supernovae
• Supernova rates and historical supernovae
• SN1987A: A Case Study

SN1987A implies that:

• Our notion of the types of stars which supernova is probably correct
• Our notion of how supernovae blow-up is probably correct
• Our notions about element production in supernovae are probably reasonable

Overall, SN1987A was a nice demonstration that we are probably on the right track concerning our understanding of Type II Supernovae.