Supernova‘s Shape Revealed just One Day After Explosion
For the first time, scientists have resolute the shape of a supernova explosion remarkably soon after its beginning – just 26 hours. An international team led by Yi Yang of Tsinghua University in Beijing used the Very Large Telescope (VLT) of the European Southern Observatory (ESO) and its FORS2 spectrograph to observe supernova SN 2024ggi in detail. This allowed them to map the geometry of the explosion using a technique called spectropolarimetry, which analyzes the polarization of the emitted radiation.
Despite being 22 million light-years away in the spiral galaxy NGC 3621 (in the constellation Water Serpent), the VLT’s 8.2-meter telescopes were able to gather crucial data.
SN 2024ggi is a Type II core collapse supernova, occurring when a massive star exhausts its nuclear fuel. The star’s core collapses into either a neutron star or a black hole, and the outer layers fall inward before being violently expelled in a rebound shock wave. This shock wave releases an immense amount of energy, creating the brilliant supernova. For a few weeks, a supernova can outshine billions of stars in its galaxy.
Yi Yang’s team’s observations with FORS2 revealed that the exploding star initially had an olive-like shape. Over the following hours,as ejected material collided with surrounding gas previously shed by the star,the shape flattened. Importantly, the axis of symmetry of the ejected material remained consistent. This suggests a common underlying mechanism may govern the explosions of dying stars and dictate their resulting shape.
