High Energy Cosmic Rays and Supernovae
The cosmic rays we are interested in at this web site have a much higher energy than those from the sun. They typically have energies of several billion electron volts (GeV), but they can have many trillion electron volts (TeV).
For the most part, they are protons, and they really do come from the "cosmos", perhaps even from outside our own galaxy. It is not precisely known how these protons get their high energy, but one possibility is that they are accelerated in very high and extensive magnetic fields surrounding, for example, the remnants of supernova explosions.
Supernovae
The background picture for this web site is a Hubble Space Telescope image of the Large Magellanic Cloud, which is a system of billions of stars about 170,000 light-years from the earth, just outside our own galaxy. The image was taken in 1996. In the image below (and the left page border) you see an interesting set of three rings. It turns out that the center of the central ring is precisely the location of a supernova that was first discovered in 1987, thereafter known as supernova 1987A.
It is thought that the two large red rings are painted in the sky by two jets of high-energy particles created by the interaction of the supernovae and it's companion, which is an object that could be either a neutron star or black hole. The black hole (if that is what it is) spins around its axis and this axis of rotation itself rotates, or precesses, tracing out a cone. The jets are created from matter from the supernovae remnant falling towards the black hole. This matter is heated and shot back into space along the two directions of the rotation axis. These jets then interact with clouds of gas that were emitted from the star long before it became a supernovae and now form a more or less spherical shell around it. The two red rings we see are the intersections of the cone swept out by the axis with this shell as viewed from earth.
If this explanation is correct, the picture is a very nice illustration of one possible source of high-energy protons.
For further information about SN1987A and other images, see:
- Hubble Finds Mysterious Ring Structure around Supernova 1987A
- Space Telescope Science Institute, Novae and Supernovae
There are many more web pages, just search for SN1987A.