Laboratory supernova


Cassiopeia A supernova remnant

Supernovae come from stars many times our sun’s mass dying. The resulting explosion leaves behind supernova remnants that are very beautiful. But why aren’t they spherical? The remnant of Cassiopeia A certainly doesn’t look spherical.

Experiments in the UK using high powered lasers show that explosions that pass through a plastic grid create “knotty” results similar to the Cassiopeia remnant. This implies that the space the supernova exploded in isn’t uniform, there must have been some kind of turbulence there for the explosion to pass through.

New supernova near Big Dipper

OK, not new. 12 million or so years ago. Anyway, up near the Big Dipper is M82, the Cigar Galaxy. After about 12,000,000 years the light of a Ia supernova has reached Earth. (that’s type 1-a) You’ll need a telescope of binoculars to see it. Here’s where it is in the night sky.

As a type Ia supernova, it isn’t caused by a large star dying and collapsing. Instead, it is caused by a white dwarf accumulating enough mass to become unstable, or 2 white dwarfs colliding (rare). Because the accreting method leads to the mass of the white dwarf increasing until it reaches the Chandrasekhar mass (about 1.44 solar masses), where the temperature of the star reaches the temperature needed to fuse carbon. Once this happens, a lot of the star explodes, releasing about 1-2 × 1044 J of energy. This leads to a standard peak luminosity, which can be used to measure the distance to the supernova (they are standard candles).