Massive supernovae

Recently, astronomers have come to realize that they needed a new class of supernovae. This class is called superluminous supernovae. The reason for this new class is that astronomers have noticed some supernovae that shine much more brightly than others, sometimes by as much as 100 times more brightly.

So what exactly is a supernova and what causes it? Well, a supernova is really an extremely bright flash in the sky, and it is caused by a massive explosion of a star. There are different types of supernovae based on the kind of explosion that is happening. For instance there is the type II supernova, which is the result of a massive star (quite a bit larger than our sun) exploding. The type Ia supernova results from a star that typically would already be thought of as “dead.” After stars explode, they typically (unless they are very large) leave a little speck of their core which can continue to burn for a very long time and it is called a white dwarf.

White dwarfs can draw energy from a nearby stars. Most solar systems, unlike ours, are part of systems of multiple nearby stars rather than a single one.) Once the white dwarf reaches a certain size it becomes unstable and explodes. These type of supernovae are important because the white dwarf essentially always explodes once it reaches this special, critical size and thus always gives off approximately the same brightness, which means it can allow us to get estimates of how far away galaxy is.

Type Ib supernovae are large stars that explode after losing some of their mass (typically to a white dwarf partner star). There are other types as well but you get the idea that stars have many interesting ways of exploding. In any case, these explosions are quite impressive, and it is not uncommon for a supernova to briefly outshine an entire galaxy!

Now imagine something that is shining 100 times more brightly than a supernova which can already outshine a galaxy; it is tremendous. This is how incredibly bright SLSN can be, and this past June, one such event was spotted. This event was so incredible that scientists had trouble accounting for all of the energy that was created.

It is now several months later and they believe that they now have the answer. They believe it was a special type of already exploded star called a neutron star. A neutron star is the exploded remnant of a star which was originally much larger than our sun but not large enough to have become a black hole. The scientists believe that this particular event was caused by a rapidly rotating neutron star, which would account for the large energy output. What an amazing thing!