What is a Supernova?
Stars which are several times more massive than our Sun end their lives in a spectacular explosion called a Supernova. The explosion occurs when the fuel for the fusion process in the core is depleted. This lack of outward pressure, which combats the inward gravitational pull, allows the star to collapse. As it shrinks, the core grows hotter and denser. New nuclear reactions begin and temporarily halt the collapse of the core. When the remaining core nuclear is basically just iron, nothing is left to fuse. Fusion in the core ends. Very quickly, the star begins its final gravitational collapse. The core temperature rises to many billions of degrees. The iron atoms are crushed together. The force of gravity is greater than the repulsive force between the nuclei of iron. The core then recoils. The energy of the recoil produces a shock wave through the star envelope. The envelope material is heated and fuses to form new and heavier elements and radioactive isotopes. The material is exploded away from the star core and is known as a supernova remnant. Many of these are seen. Here are examples.
The smaller supernovae leave behind a spinning neutron core only a few tens of miles across. Larger supernovae exert such tremendous inward shock forces that even the neutron core collapses into a black hole. It is so small and dense, that light is not fast enough to escape.
Turn Up Your Volume before you watch this video. It is an audio rendition of supernovae events in a small part of the sky. How it was done is explained below.
1. First, search for Supernovae over a long time interval.
From April, 2003 until August, 2006, the Canada-France-Hawaii Telescope (CFHT) watched four parts of the sky as often as possible. Armed with the largest digital camera in the known universe, CFHT monitored these four fields for a special type of Supernova (called Type Ia) which are created by the thermonuclear detonation of white-dwarf stars. These four fields covered roughly 16 times the area of the full Moon on the sky, or roughly 1/10,000 of the entire sky. Even though such a small fraction of the sky was monitored, 241 Type Ia Supernovae were seen during the period of observation.
The positions of all the Supernova are illustrated as time progresses. The animation is rendered at 15 frames per second, and each frame corresponds to just under a single day (1 sec of video = 2 wks of real time).
2. Assign each Supernova a note to play.
Distance to each Supernova determines the volume of the note. Closer is louder. Each Supernova follows a similar pattern of brightening and then fading. But they each also have some variations.
The pitch of the notes used was determined by the Supernova’s “stretch,” a property of how the Supernova brightens and fades. Higher stretch values played higher notes. The pitches were drawn from a Phrygian dominant scale for those who understand music theory.
3. Assign the instruments to be played.
Only two instruments were used. Notes of Supernovae in more massive galaxies were played by upright bass. Those in less massive galaxies were played by piano.
Creators of this Work – Alex H. Parker (University of Victoria) and Melissa L. Graham (University of California Santa Barbara / LCOGT).
We are stardust.
If it weren’t for Supernovae, the heaviest elements would be iron. That is the top rung of the fusion process in star cores. Because of the tremendous shock waves of supernovae, fusions of nucleii of elements heavier that iron are possible, giving us the much wider range of naturally occurring elements. Many of the elements in the rocks and minerals and our bodies came from a Supernova in our vicinity of space.