Astrophysicists from the University of Copenhagen are helping to explain the mysterious phenomenon of stars suddenly disappearing from the night sky. Their study of an unusual binary star system led to convincing evidence that massive stars can completely collapse into black holes without going supernova.

The Sun, the star at the center of our solar system, will one day begin to expand enough to swallow the Earth. It will then become increasingly unstable until it collapses into a small, dense object known as a white dwarf.

But if the mass class of the Sun were about eight times greater or more, it would probably go out in a massive explosion, such as a supernova. Its collapse would result in an explosion that would fling energy and mass into space with tremendous force, before leaving behind a neutron star or black hole. While this is a basic understanding of how massive stars die, there is much more to understand about the starry skies above them and, in particular, the spectacular deaths of these stars.

A new study by astrophysicists from the Niels Bohr Institute at the University of Copenhagen provides the most convincing evidence to date that very massive stars can die with much more secrecy and discreetness than supernovae. Indeed, their research shows that the gravitational pull of a star with enough mass may be strong enough to prevent it from exploding after it dies. Instead, the star may undergo so-called total collapse.

“We believe that the star’s core may collapse under its own weight, as occurs for massive stars in the final stages of their lives. But for stars eight times more massive than the Sun, rather than contraction resulting in a bright supernova explosion that will dwarf its home galaxy, the collapse is expected to continue until the star collapses into a black hole.” ,” explains first author Alejandro Viña-Gómez. He was working as a postdoctoral researcher at the Niels Bohr Institute when this research began.

Facts and myths: Fading stars

In our time, there have been many observations of stars that have inexplicably disappeared.

The Nothing Survey, led by astrophysicist Chris Kochanek, is an example of a research effort that actively searches for vanishing stars and explains their extinction.

The curious reader can also look for historical explanations. This is often associated with bright stars that suddenly disappear in supernova scenarios. However, there are other stories about the sudden disappearance of stars, such as the Greek myth associated with the Pleiades star cluster, commonly known as the Seven Sisters. The Pleiades legend tells about the seven daughters of the titan Atlas and the fairy Pleione. According to legend, one of his daughters married a human and went into hiding; This provides a very unscientific but good explanation for why we see only six stars in the Pleiades.

This discovery relates to the phenomenon of star disappearance that has intrigued astronomers in recent years, and may provide both a clear example and a plausible scientific explanation for such phenomena.

“If one stands and looks at a visible star that is completely collapsing, it may seem as if one is watching a star suddenly fade out and disappear from the heavens at just the right moment. The collapse is so complete that no explosion occurs, nothing is thrown out, and no one will be able to see a bright supernova in the night sky. Recently astronomers observed the sudden disappearance of brightly shining stars. We cannot be sure of the connection, but our results from the analysis of VFTS 243 bring us closer to a reliable explanation,” says Alejandro Viña-Gómez.