Credit: B.J. Fulton (Las Cumbres Observatory)
Looking for supernovae helps confirm or challenge what we know about the lives of massive stars.
Young, massive stars explode as type Ib, type Ic, and type II supernovae. So we expect to see lots of supernovae in places where stars have recently formed. The arms of spiral galaxies are thought to be the best place to find young massive stars. When we look at these regions of space, we find lots of supernovae.
It is quite common for galaxies to collide with each other. These energetic events can also trigger star formation. This makes interacting galaxies a good place to find supernovae too. Places like the Milky Way's nearby 'satellite' galaxies, the Large and Small Magellanic Clouds.
It is a bit more tricky to predict where we will see type Ia supernovae. What we know about them suggests we should find them where we also see older stars. This is because it takes several billion years for a star to become a white dwarf. But they have also been found where we expect to see young stars. For example, in the spiral arms of a galaxy.
Remember we expect only one or two stars in the Milky Way to explode every 100 years. So if you want to try hunting for supernovae yourself, bear this in mind. If you find a likely part of a galaxy (or even a massive star like Betelgeuse), you may not see a supernova any time soon. This is why surveys are so useful for scanning huge areas of the night sky very quickly. That way we can study many, many galaxies at the same time. The more galaxies, the more stars. The more stars, the greater chance of one exploding!