Here at ICRAR, PhD students Toby Potter and Giovanna Zanardo are studying the formation and evolution of an exciting young supernova remnant.
A supernova is an exploding star. The explosions come in two forms, accretion/detonation and core collapse. The accretion supernovae, traditionally classified as Type Ia, occur when material accreted onto white dwarf star reaches a critical density, enough to trigger a thermonuclear explosion. The second type of supernova, known also as Type Ib, Ic, and Type II, is powered by the runaway gravitational collapse of a star that has run out of fuel.
Supernovae and their associated remnants play an important role in stellar feedback, stellar formation, and the formation of heavy elements.
In 1987 a Type II supernova appeared in one of the Milky Way's satellite galaxies, the Large Magellanic Cloud. As the closest supernova to occur in the modern age it has since been monitored extensively at all wavelengths. It was also the first supernova for which we have neutrino measurements. These measurements were used to place an upper limit on the electron neutrino mass.
The kinetic energy released from SN 1987A has been estimated to be around 1044 Joules or 1016 (that's 1 with 16 zeros) trillion megatons of TNT. This energy took the form of a shock that began moving away from the collapsing core at a tenth the speed of light. A few minutes after core collapse, the shock broke through the surface of the star. An ultraviolet flash from the shock breakout lit up material surrounding the star and revealed a beautiful three-ring structure. The central ring is known to be the waist of a much larger hourglass. The ring and hourglass are believed to have formed around 20,000 years prior to explosion.
At present, the expanding shock has reached the central inner ring and is interacting with it. The superheated shock is heating material in the ring to around 1 Billion degrees Kelvin. The heated material glows brightly in X-Rays. At the shock front electrons are accelerated to almost the speed of light where they emit synchrotron radiation that radio telescopes such as ASKAP and the SKA will be able to detect.
Such a wealth of data on SN1987A makes it a superb laboratory for studying the physics of supernova remnants. Using radio and X-Ray observations as well as simulations we are studying the morphology and evolution of the expanding shock front in order to gain further insight into the hydrodynamics of supernova remnants and the particle acceleration mechanisms responsible for producing synchrotron emission at the shock front.
