An international team of astronomers has shown that white dwarfs, that is, stars that go through their last stage of evolution, can reactivate and explode, which constitutes the first proof of their involvement in the explosions known as type Ia supernovae. The scientists verified, through the Integral gamma ray telescope, the presence of radioactive elements disintegrating in the environment of the dying star, that is, the chemical remnant of one of these explosions.
The telescope detected gamma rays from radioactive nuclei created during the explosion of a Type Ia supernova , the result of the interaction of a white dwarf with a companion star. The researchers not only found the signature of the cobalt decay, but they did so in the exact amount predicted by the models, according to which, the carbon and oxygen of a white dwarf should fuse, during the explosion, into radioactive nickel, which in turn would disintegrate into radioactive cobalt and, much later, into stable iron.
“Integral is perfectly capable of detecting the chemical signature of the fusion, but we have had to wait more than ten years to hunt down a nearby supernova , in a once-in-a-lifetime opportunity”, commented one of the authors of the finding. The moment in question occurred on January 21, 2014, the day a group of students discovered a Type Ia supernova in the neighboring galaxy M82, just about 11.5 million light-years from Earth.
The discovery therefore confirms the theory about the origin of type Ia supernovae and gives rise to new investigations that delve into the trigger for these explosions.
