| | Supernovae Neighbours
 A supernova is an exploding star and releases enormous amounts of energy and, perhaps more importantly, new radioactive elements that can quickly decay. If our Sun had a supernova neighbour during its formation then these radioactive elements could have been added to the Solar System and dramatically change the nature of the forming planets.
Supernovae are the death-throws of stars, occurring once a star has too little fuel to support its own mass and collapses in on itself. Different stars can become supernovae at very different times depending on their mass. Large stars, more than 30 times the mass of our Sun, only last a few million years before they explode as supernovae. Massive O and B stars are frequently observed in clusters of young stars and may form supernovae whilst solar mass stars are still surrounded by disks of dust and gas.
The importance of a nearby supernova during our Solar System's formation is two-fold. Firstly the shockwave emanating from the supernova will compress gas clouds and might trigger the collapse that leads to the formation of new stars. Secondly, and just as important, is that supernovae lead to the generation of new radioactive isotopes, since they produce large numbers of neutrons that are captured by atoms to make new heavier atoms. At least some of these radioactive isotopes, in particular 26-aluminium, decay quickly and produce large amounts of heat. If mixed into the Sun's disk of gas and dust, the solar nebula, and incorporated into the bodies forming in the disk, these radioactive materials could cause objects the size of asteroids to melt, and thus to change.
Finding evidence for short-lived radioactive elements provides us with a means of investigating our Sun's astrophysical surroundings during its formation. Certain isotopes, such as 60-iron, that decays relatively quickly, could only have formed within a nearby supernova.
|
