There are few astronomical events as powerful as a supernova. Among supernovae, there are different types, and scientists think they might have cracked the mystery of one of the brightest: superluminous supernovae.
Their name obviously implies that they are brighter than your regular supernova (hundreds of times in some cases), and they also last for longer. These characteristics could make them easier to spot, but actually, these events are pretty rare, with only a dozen examples observed so far.
For this reason, an international team of astronomers has been using the Great Canary Telescope on the Canary Islands to scan the sky, ready to start observing a superluminous supernova as soon as it happens. After getting a tip from the Dark Energy Survey of an interesting event, which they called DES14X3taz, the team followed the event to discover that it didn’t look like at all like other supernovae.
DES14X3taz, which is located 6.4 billion light-years away, showed a first sudden brightening followed by a dimming phase before the system began to get brighter again.
“We think that a very massive star, some 200 times the mass of the Sun, collapses to form a magnetar,” explained Mathew Smith, a postdoctoral researcher at the University of Southampton, in a statement. “In the process, the first explosion occurs, which expels into space a quantity of matter equivalent to the mass of our Sun, and this gives rise to the first peak [in luminosity].
“The second peak occurs when the star collapses to form the magnetar, which is a very dense object rotating rapidly on its axis, and which heats up the matter expelled from the first explosion. This heating is what generates the second peak in the luminosity."
The research, which is published in the Astrophysical Journal Letters, is the first attempt at a complete look at the evolution of superluminous supernovae. This understanding could turn these events from interesting to useful – by standardizing their properties, we could use them to independently measure the distances of their host galaxies.
And the nature of these galaxies might play a role in the chance a star has to end up as a superluminous supernova. Most of these supernovae have been found in small galaxies poor in heavy elements, another mystery that only more observations can solve.