A New View of Supernovae
When a star explodes, the extreme brightness sometimes outshines its host galaxy. After two supernova types were initially sufficient to classify the stellar explosions, observers are now confronted with an almost unmanageable variety. The first part of this article is mainly about the measurement data of observed supernovae. In the second part, the increasingly subtle theoretical models and computer simulations are presented.
Star explosions were observed thousands of years ago, but mankind has long puzzled over the cause of these celestial phenomena. It's only been 135 years since we've known that it's not about the flaring birth of a new star - quite the opposite: a star ends its existence in a particularly spectacular way during a stellar explosion.
On August 20, 1885, Ernst Hartwig discovered such a celestial event in the Andromeda galaxy (Messier 31, M31 for short). While he may not have been the first person to see this burst of brightness, he communicated the apparition in a telegram on August 31 after being certain it was not reflected moonlight. Therefore, the first extragalactic stellar explosion called S Andromeda is attributed to him. However, it was only thanks to Knut Lundmark that we realized that this was something very special. In 1919 he estimated the distance to M31 at 700,000 light-years; about four times closer than the Andromeda Galaxy actually is, as we now know. Despite this error, it was clear that S Andromeda must have been more than 1000 times brighter than a normal nova…