Astronomers have found that this scarring can tell them a great deal about the binary star system as it was before the explosion even occurred. With most stars being a part of multiple star systems, this is of particular interest to scientists trying to understand their evolution.
But not all stars will go supernova as they run out of fuel – only the more massive ones have enough self-gravity to actually explode. A star needs to have roughly eight times more mass than our Sun for what is known as a core-collapse supernova to occur. And it is gravity that drives the processes that lead to this dramatic ending.
For most of its life, a star exists in a state known as hydrostatic equilibrium, where the inward and outward forces on the star are finely balanced. Gravity draws in surrounding matter towards the star’s core, while radiation pressure from the heat being generated within pushes outwards and prevents the star from imploding.
In fact, these two forces are inextricably linked. If the core were to cool a little, the inward force of gravity would exceed the outward radiation pressure and the star would contract. The contraction would increase the temperature and pressure of the star again, returning it to equilibrium.
The real excitement comes as the star runs out of fuel and can no longer support itself against its own weight. Within a split second the core collapses, sending a shockwave radiating out through the star blowing it apart and causing one of the most energetic events we see anywhere in the Universe.
How much energy are we talking about? Roughly as much as the Sun will generate over something like 10-billion years. All produced in barely a fraction of that time. If there is a nearby companion star, it can be hit by debris from the explosion. When this happens, the surface heats up and causes the star to swell, a bit like having a burn blister on your skin.
The star blister can be 10 or even 100 times larger than the star itself, but it lasts only for a very short time. Within a few decades, the blister heals, and the star shrinks back to its original form.
The team of Australian and Japanese astronomers, including post-doc researcher Dr Ryosuke Hirai from Monash University and the ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav), have carried out hundreds of computer simulations to investigate how companion stars inflate depending on their interactions with nearby supernovae. They then applied their results to SN2006jc, a supernova that was first seen by amateur astronomers and preceded by something that was, well, a little confusing. TO READ ENTIRE ARTICLE,
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