Astronomers discover an unusually bright supernova

Astronomers have discovered a rare, ultra-luminous supernova whose intrinsic brightness, at peak luminosity, was 100 billion times that of the Sun. This special type of stellar explosion, called a self-interacting supernova or super-luminous supernova, results from exploded material interacting with previously puffed-off layers from the star. The type of progenitor star whose fate it is to end this way is called a luminous blue variable. A well-known example in our own galaxy is Eta Carinae, pictured below.

Luminous blue variable star, Eta Carinae, could end its life as a super-luminous supernova

Measured to be about 3.7 billion light-years away, the extreme brightness of the newly discovered supernova allowed astronomers to detect it using a relatively small robotic telescope that’s part of the ROTSE Supernova Verification Project (RSVP). So far, RSVP has found five of the 12 known supernovae of this type. To give you some idea how rare these objects are, consider how supernovae are named. This particular object is called SN 2008am. The numbers tell us the year it was discovered, while the letters tell us the order in which it was discovered. The first supernova detected in 2008 was called 2008a, the second 2008b, and so on. This makes SN 2008am the 39th supernova discovered that year. I don’t know the total number of supernovae that were discovered in 2008, but the RSVP website indicates an object named SN 2008io, which means there were at least 249. (All of those are in other galaxies, by the way — we haven’t observed a supernova in our own galaxy for about three hundred and fifty years.) So, 12 super-luminous supernovae out of hundreds of all types observed annually makes these particular objects rare indeed.

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