One of the most massive and bright stars in the local universe has mysteriously disappeared from view.
The star – located around 75 million light years away, in the Kinman Dwarf Galaxy – can no longer be seen, and scientists are not sure why.
Researchers spotted the mysterious vanishing when they attempted to look at the star to learn more about how very massive stars die. The star had been extensively studied between 2001 and 2011, through observations showed that it appeared to be at a late stage of its life, and so seemed a perfect target for the new research.
"Instead, we were surprised to find out that the star had disappeared!" said Andrew Allan, the Trinity College Dublin scientist who led the study, in a statement.
It may be that the star has lost its brightness and become obscured by dust. But, more unusually, the star could have died out, without exploding into a supernova, and instead collapsing into a black hole.
“If true, this would be the first direct detection of such a monster star ending its life in this manner," said Mr Allan.
Such a discovery could change our understanding of how massive stars die. In our current story, they are expected to erupt into a supernova as their life comes to an end – but that appears nto to have happened.
The Kinman Dwarf galaxy is found in the constellation of Aquarius, and is so far away that astronomers are not able to see specific stars. Instead, they can pick up the specific signatures of some of them.
Those signatures showed that there was a star known as a "luminous blue variable", which is 2.5 million times brighter than our Sun. Those stars are in particularly frantic parts of their lifecycle, and so change quickly – but tend to leave behind some signatures that can be picked up by scientists.
But when researchers looked back to the galaxy in 2019, they found neither any trace of the star, or of the supernova that would indicate its death. Instead, the object appeared to have disappeared
"It would be highly unusual for such a massive star to disappear without producing a bright supernova explosion,” said Mr Allan in the same statement.
To be sure they had not simply missed the expected signature, researchers turned a series of instruments on the European Southern Observatory's Very Large Telescope towards the spot where it should have been. But despite months of work and a variety of different attempts to find the star, they were unable to find any trace of it.
“We may have detected one of the most massive stars of the local universe going gently into the night,” said team-member Jose Groh, also of Trinity College Dublin.
Researchers then checked through old archival data and found that the star had been undergoing a busy period of activity that probably came to an end in 2011.
They hope that further work, with yet more instruments, could be able to show distant stars in more detail and help reveal what happened to the disappearing star, and others like it.