Cosmic catastrophe - 4

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Death by Supernova

Supernovae are extremely violent events,

1. Type I: thermonuclear runaway in a red-dwarf/white-dwarf binary
2. Explosive disruption of stars with M > 8 solar masses

At its brightest, a supernova outshines the Sun by a factor of >1 billion
More important, from the point of view of life, supernovae generate high-energy particles and gamma rays (high energy radiation). These might lead to genetic mutation if the supernova were sufficiently near the Sun. (This was suggested as a dinosaur destruction mechanism.)

At present, such an event is unlikely, since the nearest potential Type I supernova is at least 50 light years distant, and the nearest Type II ~1500 light years away (in Orion). However, the Sun orbits the Galactic Centre once every 100 million years; every ~30 million years, or so, it passes through a Galactic spiral arm - major sites for star formation, regions with many, short-lived massive stars.
Spiral arms have also been suggested as precipitating `comet showers'
- gravitational perturbations which send comets from the Kuiper and Oort clouds into the inner Solar System.

A supernova remnant - this filigree structure of tenuous gas is all that remains of a star much more massive than the Sun

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The rings of SN 1987A (HST)

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