Supernovae are the result of a star dying in an explosion

Supernovae come into two broad categories, called types, depending on the observed spectra. The two types also are theorized to be caused by different classes of stars with different mechanisms

  • Type I
    • The observed spectrum has no evidence of hydrogen
    • Origin: a white dwarf reaches the Chandrasekhar limit where electron degeneracy stops supporting gravitational collapse leading to thermonuclear runaway explosion
  • Type II
    • The observed spectrum has strong emission and absorption features due to hydrogen
    • Origin: a massive star (greater than 8 solar masses) ceases core-fusion when iron is produced, leading to gravitational collapse. The infalling matter (somehow) rebounds and causes the explosion (the how here is still being investigated)

Sub-types of each exist dependent on other elemental emission/absorptions observed in the spectra (e.g., Type Ib does not have the 635 nm silicon line whereas Type Ia does have that line) and the duration of the light curve.

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