The mystery of the missing star in the Andromeda Galaxy – What really happened?

The case of a missing star from the Andromeda Galaxy has emerged as one of the most intriguing astronomical mysteries of recent years. The yellow supergiant known as M31-2014-DS1 gradually brightened in 2014, only to disappear without a trace from the night sky over the following years. While two research teams are currently investigating the phenomenon, the precise events remain unresolved.

Stars are generally extremely stable objects, with lifespans of billions of years, meaning they rarely undergo dramatic changes in a short period. It is not unheard of for a star to dim or end its life in a colossal supernova explosion before collapsing into a black hole or neutron star. However, it is exceptionally unusual for a star to simply vanish without a trace. This is precisely what makes the disappearance of a star from the Andromeda Galaxy so remarkable.

As reported by IFLScience, M31-2014-DS1 was a yellow supergiant with a mass roughly 12–13 times that of the Sun. Scientists observed it gradually brightening in 2014, yet by 2018 it had completely vanished from view. The case is made more complex by the fact that no conspicuous supernova explosion was observed, raising questions that both research teams are striving to answer.

The missing star and the “failed supernova” hypothesis

One team, analysing data from the James Webb Space Telescope (JWST) and the Chandra X-ray Observatory, concluded that the missing star may represent a striking example of a so-called “failed supernova”. This suggests that the star collapsed directly into a black hole without undergoing the dramatic explosion typically associated with supernovae. According to theory, stars above a certain mass can indeed end their lives in this quiet manner.

During observations, the researchers detected an extraordinary source of light where the star had previously been, but it only emits around 7–8% of the original luminosity. They also observed a shell of dust extending between 40 and 200 astronomical units, which is thought to be the remnants of previously ejected material.

The team proposes that the faint light may originate from the fallback of ejected material and accretion onto the newly formed black hole. The model is not perfect, however, as no X-ray emission indicative of accretion has been detected. The researchers suggest this could be due to the dense dust currently absorbing X-rays, an effect that may diminish as the structure expands.