Stars do not shine forever, but have a limited lifetime. They gain their energy through nuclear fusion of lighter elements such as hydrogen and helium. Once the nuclear fuel supply is exhausted, the fusion products are further used to gradually produce heavier elements. In massive stars, this process can continue all the way to the element iron. However, no more energy is extracted from the fusion of iron. As a result, the radiation pressure that supports the star from within and counteracts its own gravity diminishes. If this pressure disappears completely, the star collapses, which leads to an enormous explosion in particularly massive stars. This event, which can only be caused by stars with more than eight times the mass of the Sun, is called a type II supernova: a so-called core-collapse supernova, in which the core of the star can no longer withstand the gravitational pressure. The consequence is an enormous brightness outburst which can outshine a whole galaxy.
The supernova SN2023ixf discovered in the night of May 19, 2023 by the Japanese researcher Koichi Itagaki belongs to this category. In the galaxy Messier 101, also known as the Fire Wheel Galaxy, a new point of light can now be seen for a few days and weeks in one of the spiral arms. It will increase in brightness in the coming days before slowly fading back into one of the many spiral arms of its home galaxy. Currently, this stellar explosion is so bright and cosmically close to Earth that the event can be followed live with a small telescope and a camera. It can be found in the constellation Ursa Major (Great Bear), which is high in the evening sky at this time of year," says Florian Rünger, an observer and doctoral student in the astrophysics group at the Institute of Physics and Astronomy at the University of Potsdam.
23-05-2022 / No. 052
