Something new in the sky
Around 500 million light-years away in the constellation Sculptor lies a rather peculiar looking galaxy, known as the Cartwheel galaxy. It was once a normal spiral galaxy that underwent a head-on interaction with a smaller companion galaxy several million years ago, giving it its signature cartwheel appearance. But there are other curious things about this object. Something interesting is taking place in the lower left corner of the right image, captured in December 2021 with ESO’s New Technology Telescope (NTT): a supernova. The image on the left, taken in August 2014 by the Multi Unit Spectroscopic Explorer (MUSE) mounted on ESO’s Very Large Telescope (VLT), shows the galaxy before this supernova took place.
This event, called SN2021afdx, is a type II supernova, which occurs when a massive star reaches the end of its evolution. Supernovae can cause a star to shine brighter than its entire host galaxy and can be visible to observers for months, or even years — a blink of an eye on astronomical timescales. Supernovae are one of the reasons astronomers say we are all made of stardust: they sprinkle the surrounding space with heavy elements forged by the progenitor star, which may end up being part of later generations of stars, the planets around them and life that may exist in those planets.