In a distant galaxy NGC 1260, some 250 million light-years away, occurred the most powerful explosion ever seen anywhere. Named SN2006gy, this supernova certainly stands apart. It was so energetic, it’s often called a hypernova or quark-nova. It was quickly observed by NASA’s Chandra X-ray Observatory and large ground based observatories, with speculation rife that it could be a longsought new type of explosion. Supernovae come in two main varieties. Type I involves a double star system. Here a common ultra-dense white dwarf star gains stellar wind material from an orbiting companion. When enough atoms accrue on its surface, its newly growing mass raises its core temperature so that carbon fusing abruptly begins in a sudden thermonuclear conflagration, destroying the star and briefly outshining all the stars in its galaxy.
By contrast a Type II supernova involves a single massive star in its old age, whose core no longer has the outward-pushing energy to prevent the core collapsing in on itself. The collapse rapidly builds up explosive heat, which then ignites everything. The twisted filaments of the star are blown off at 1600kms /sec while the core implodes, forming an ultra-dense neutron star only a few kilometres wide. Dramatic yes, but then astronomers began to think of a much rarer potential candidate that could produce a much more violent explosion, an extremely rare type of star that was 150/200 times the mass of our Sun, near the absolute upper limit of what is possible. These stars have but one destiny, they never live long. The high temperatures and pressures in their cores make their nuclear fusion almost a runaway. Such stars go supernova within 5 to 10million years. SN2006gy’s star was so massive, its fierce output of intense gamma rays produced matter/antimatter pairs. Not good for its health and stability, Matter and antimatter ignite on contact, releasing 100% of their combined mass as pure energy, compared to only 0.7% mass-to-energy efficiency in an average star, like our Sun.
This very rare supernova referred to as a “pair-instability supernova” releases 10 million trillion times the output of the Sun and leaves nothing behind; no neutron star nor a black-hole. Hypernovae like SN2006gy do remind us of another contender for the biggest bang ever, lurking much closer to home, the enormous Eta Carinae. This super-luminous hyper heavy star is still in its pre-supernova state and is located in our galaxy, 32,000 times closer to us than SN2006gy! When it explodes tomorrow or in a million years’ time it will appear a billion times brighter than SN2006gy enough to be visible in daytime; it will pose no threat to mankind, but will be a spectacular and dramatic event to witness.