Massive stars have extreme novas {supernova}|. For several months, star radiation is 10^9 times Sun radiation. Only 1% of stars become supernovas, so one galaxy has one supernova every 50 years. Sumerians saw a supernova (Mul Nun-ki) [-3000] in Vela. A supernova [185] lasted 20 months and was as bright as Moon. Supernova [393]. A supernova [1006] lasted years and was as bright as Moon. A type-2 supernova [1054] formed the Crab nebula. Supernova [1181]. Tycho observed a Type-1a supernova [1572], as bright as Venus. Kepler observed a supernova [1604].
Supernovas make all titanium through iron nuclei, mostly carbon, oxygen, silicon, magnesium, and iron. Supernovas also make five percent of elements heavier than iron.
Physical Sciences>Astronomy>Star>Kinds
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Date Modified: 2022.0224