Mystery as massive star ‘vanishes’ without a trace

  • Mystery as massive star ‘vanishes’ without a trace

Mystery as massive star ‘vanishes’ without a trace

Astronomers have been tracking the luminous blue variable star located in the Kinman Dwarf galaxy since 2001.

The seemingly sudden disappearance of the star was unusual, as, according to the researchers, such a massive stellar body would be expected to explode in a cataclysmic supernova upon ending its life cycle.

Based on their observations and models, the astronomers have suggested two explanations for the star's disappearance and lack of a supernova, related to this possible outburst.

This could explain why the star appeared so bright during those early observations - still, it does not explain what happened after the outburst that caused the star to vanish. It's small, which makes things hard, to begin with, and images of the dwarf galaxy from Hubble reveal how hard it is to pick out individual stars.

"If true", says team leader and PhD student Andrew Allan of Trinity College Dublin, Ireland, "this would be the first direct detection of such a monster star ending its life in this manner".

An unstable massive star has suddenly vanished from view, and astronomers aren't sure if it collapsed into a black hole or is playing peek-a-boo behind galactic dust.

Andrew Allan of Trinity College Dublin, along with colleagues from Chile and the USA, pointed ESO's Very Large Telescope (VLT) in Chile's Atacama Desert towards the distant galaxy in 2019 for a new survey.

Located 75 million light-years or 440,896,900,000,000,000,000 miles from Earth, the galaxy's individual stars are too far away to directly observe. The spectrum showed that the distant galaxy contained a late-stage blue variable star that is 2.5 million times brighter than the sun.

Astronomers have been baffled by the disappearance of a massive star they had been observing.

"We may have detected one of the most massive stars of the local Universe going gently into the night", comments team-member Jose Groh of Trinity College Dublin, who was one of the authors of the new paper.

Further observations will be needed to determine the fate of the mysterious luminous blue variable star that once brightened the Kinman Dwarf. It is possible that the star collapsed into a black hole without first triggering a supernova - a rare event, even in the context of dying stars. What seems to be the most likely scenario is that the star was undergoing an outburst at the time when it was previously observed.

However, the researchers can't rule out the possibility that the star went supernova in the period between 1995 and 1998 when no observations were available. (Sometimes, this looksdownright lovely.) Following the blast, the dense core of leftover stellar material may collapse into a black hole or aneutron star - two of space's most massive and mysterious objects. Image credit: NASA / ESA / Hubble / J. Andrews, University of Arizona.

"This would be a rare event: our current understanding of how massive stars die points to a lot of them ending their lives in a supernova". ESO is also a major partner in two facilities on Chajnantor, APEX and ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre Extremely Large Telescope, the ELT, which will become "the world's biggest eye on the sky".