Washington: Texas astronomers have discovered one of the most intrinsically bright exploding stars ever observed — Supernova 2008am.
The research by graduate student Emmanouil ‘Manos’ Chatzopoulos and J. Craig Wheeler of The University of Texas at Austin has revealed that this supernova is the brightest ‘self-interacting’ supernova yet discovered.
The supernova was discovered by the ROTSE Supernova Verification Project (RSVP, formerly called the Texas Supernova Search), which uses the 18-inch robotic ROTSE IIIb Telescope at The University of Texas.
It was followed up by astronomers using some of the world’s largest ground-based telescopes, as well as telescopes in space, in a variety of wavelengths.
Supernova 2008am is 3.7 billion light-years away. At its peak luminosity, it was over 100 billion times brighter than the Sun.
It emitted enough energy in one second to satisfy the power needs of the
United States for one million times longer than the universe has existed.
In-depth studies of this supernova are helping the team to understand the science behind this new class of exploding stars.
Chatzopoulos’ detailed analysis of the light from SN 2008am revealed that it is not a pair-instability supernova, the explosion of a massive star the light from which is powered by radioactive decay.
Rather, this supernova’s extraordinary luminosity most likely comes from interaction between the debris from the star’s explosion running into an envelope of gas around the star that the star had previously ejected. This model is called ‘circumstellar interaction’.
The researchers suspect that the progenitor star for this supernova might have been of the type known as a ‘luminous blue variable’. These massive stars puff off layers of material in episodes. The most famous example is Eta Carinae.
Prior to this discovery, the Texas Supernova Search found the first two ‘brightest supernovae ever’ — SN 2005ap and 2006gy.
The group has found five of the dozen published examples of this new class of stars, which it has dubbed “super-luminous supernovae”, or SLSNe.
“We’re now in the process of converting our discoveries into real science rather than just a new thing,” said Wheeler.
“That makes it a little bit less flashy, but of course that’s where the science really is, digging deeply into the nature of these very bright events. This new supernova has given us important new clues to their behavior,” he added.
The finding appears in the current issue of The Astrophysical Journal.