A supernova, is the final cataclysmic event in a star’s lifecycle, the moment when it explodes, propelling gas and dust into the interstellar medium in a gigantic shockwave of energy and light that can be seen across the vastness of space - if we happen to be looking at the right time and in the right place. It is an event of enormous power and release of energy and matter that occurs in the silence of the vacuum of space.
A supernova may be visible for weeks or months in most cases and being such a rare find, astronomers must gather information rapidly, it is estimated that only three such events have been observed in the last thousand years.
The supernova in question here is a super luminous supernova which can be 10 to 100 times brighter than the average supernova. This particular supernova, affectionately named DES15E2mlf, was found by the Blanco telescope in Chile. DES15E2mlf has an interesting past. Born 3.5 billion years after the big bang era during a time of peak star formation, known to astronomers as the Cosmic High Noon.
What is increasingly interesting is that anything formed during the Cosmic High Noon is around 10 billion years old and around 10 billion light years away and subsequently too far away for us to observe. We are only able to see DES15E2mlf because it is three times brighter than our own galaxy.
According to the Monthly Notices of the Royal Astronomical Society paper, DES15E2mlf has changed the way we think about super luminous supernovae. Previous supernovae of this calibre have formed in lower mass galaxies or dwarf galaxies, but this supernova is from a galaxy that has been described as fairly massive and normal looking.
This link between super luminous supernovae and smaller sized galaxies is explained by the smaller concentrations of metals and other elements heavier than helium present in such galaxies. These elements were thought to prevent such large supernovae but DES15E2mlf’s galaxy would have been full of these elements. Dr Ryan Foley from the University of California, Santa Cruz explains:
“Even high-mass galaxies had low enough metal content to create these extraordinary stellar explosions. It's important simply to know that very massive stars were exploding at that time, what we really want to know is the relative rate of super luminous supernovae to normal supernovae, but we can't yet make that comparison because normal supernovae are too faint to see at that distance.”
This super luminous supernova is giving scientists a unique look at an ancient galaxy some 10 billion light years away.
Header: The yellow arrow marks the superluminous supernova DES15E2mlf in this false-colour image of the surrounding field. This image was observed with the Dark Energy Camera (DECam) gri-band filters mounted on the Blanco 4-metre telescope on December 28, 2015, around the time when the supernova reached its peak luminosity.
Credit: D. Gerdes / S. Jouvel