It’s one of the most powerful phenomena we know: a supernova.
A star explodes when it has used up all the hydrogen. After that, it no longer has enough energy inside to counteract the force of gravity, and thus collapses under its own weight – eventually exploding in a massive energy discharge.
After that, only the nucleus remains, which turns into either a black hole or a neutron star. The rest of the star disappears into space in the form of nebulae.
The explosion is so powerful that it could make an entire galaxy fade by comparison. The dwarf stars that collapse in particular, the so-called thermonuclear supernovae, are massive and absolutely destructive. At least that’s what astrophysicists thought — until now.
The star that survived a supernova
group of astronomers He was so surprised When the long-awaited data about the thermonuclear supernova of the Hubble Space Telescope SN 2012Z landed in their computers.
The star survived the explosion. And not only did it survive – it was even brighter than it was before the supernova explosion.
“We expected to see one of two things when we got the latest Hubble data,” he said. Astrophysicist Curtis McCauley says:. “Either the star has completely disappeared or it is still there, which means that the star we saw in the images before the explosion was not the one that exploded. No one expected to see a star shine brighter. It was a mystery.”
These thermonuclear supernovae are also called Type Ia supernovae. It is among the most important criteria for astronomers when measuring cosmic distances.
However, astrophysicists don’t know exactly what causes thermonuclear supernovae. There is agreement that they are the result of completely rupturing white dwarf stars – stars the same size as the Earth, but with a mass like the Sun.
The supernova that failed
One theory is that a white dwarf steals matter from its companion and when it gets too heavy, thermonuclear reactions ignite and explode.
SN 2012Z is a special type of thermonuclear explosion called an Iax supernova. They are weaker cousins of the more common type Ia.
Because they are weaker and explode more slowly, researchers have theorized as to whether supernovae failed. This theory may now be confirmed.
Astronomers believe that the reason the star shone brighter after the supernova explosion was because the star had swelled into a more focused state. Because the supernova wasn’t powerful enough to rip all the matter apart, some returned to the star in what’s called a bound remnant.
Astronomers predict that over time the star will slowly return to its original state – even larger and less negative. Paradoxically, for white dwarf stars, the larger the mass, the smaller their size.
With the discovery of the zombie star SN 2012Z, astronomers will redefine how a supernova is perceived, and what causes it to explode.
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