Failed supernovae: the invisible death of stars

Did you know that some stars, eight times the size of our Sun, disappear from the sky without a trace?

Stars, like everything, have a life cycle. When matter collapses in their core, they explode as supernovae, releasing immense light and energy before becoming black holes or contributing to the formation of new stars. However, not all stars follow this pattern. Some massive stars have been observed vanishing without their characteristic explosion. This anomaly, known as 'failed supernovae,' marks a star’s silent and invisible demise. The most recent example occurred in October in the Andromeda galaxy, neighbouring our Milky Way. There, a star, called by the complex name of M31-2014-DS1, with a mass equivalent to twenty times that of the sun, had begun to increase its luminous intensity more and more. Although researchers had expected such a large star to generate an intense glow of light, it suddenly extinguished, disappearing completely from the telescopes’ view: an unexpected death of the star that shocked our astronomers. So, why do some stars skip the supernova phase? Astronomers theorize that factors like rotational speed and metallicity (the abundance of heavy elements) might influence whether a star collapses directly into a black hole. Being a very complex phenomenon and far from easy to observe, we do not have much information about it, but it is speculated, however, that the case of failed supernovae is much more common than we might think; as it is the cause of the death of at least 20% of the stars in our galaxy. The issue isn’t just missing the light show of a supernova but that stars collapsing directly into black holes retain essential elements needed for forming new stars, potentially reducing their numbers and affecting our galaxy’s future.

By Andrea Alparisi, 3L – Liceo Scientifico Vittorio Veneto, Milan