Bright, Massive Star Vanishes Without a Trace

Back in 2019, astronomers observed a gigantic star that shined about 2.5 million times more than the Sun pulling off a vanishing act.  

Now, in a new paper published in the journal Monthly Notices of the Royal Astronomical Society, a team of astrophysicists has detailed their attempt to solve the case of the disappearing star by proving a few possible explanations.  

Of these, one odd ending singles out: perhaps, the massive star died and collapsed into a black hole without exploding into a supernova first, which is a rather unprecedented act of stellar death.  

“We may have detected one of the most massive stars of the local universe going gently into the night,” Jose Groh, an astronomer at Trinity College Dublin and a co-author of a new paper on the star, said in a statement.

“If true, this would be the first direct detection of such a monster star ending its life in this manner,” study lead-author Andrew Allan, also from Trinity College, said in the statement.  

Luminous Blue Variables  

The star, located approximately 75 million light-years away in the constellation of Aquarius, was also analyzed between 2001 and 2011. The celestial object was a spectacular instance of a luminous blue variable (LVB), which is a gigantic star getting closer to the end of its life and prone to capricious variations in brightness.  

Stars such as this are rare, with only a few confirmed to exist in the Universe so far. Back in 2019, Allan and his colleagues wanted to discover more about the faraway LBV’s enigmatic evolution by using the European Southern Observatory’s Very Large Telescope. The team had surprisingly learned that the star has completely disappeared from its host galaxy.

An artist’s impression of the the luminous blue variable star that mysteriously vanished. [Image: ESO/L.Calçada]
Typically, when a star much larger than the Sun approaches its end of life, it explodes into a massive supernova. These blow-offs are easy to observe, as they cover the sky around them with ionized gas and powerful radiation for many light-years in all directions.  

Where Did it Go?  

After the explosion, the thick core of leftover stellar material may collapse into a black hole or a neutron star, which are both very mysterious and gigantic celestial objects. However, the missing star left no such impact, but it just vanished completely.  

To analyze this unprecedented event, the team of researchers looked back at prior observations of the orb taken in 2002 and 2009. They found out that the star had been undergoing a powerful explosion period during these years, emitting massive amounts of stellar material at a faster rate than normal.  

LBVs can suffer multiple outbursts like this in their uncertain end-of-life period – the scientists wrote in their paper – making them glow more brightly than usual. The explosion probably ended after 2011, the team said.  

This could explain the reason behind the stars’ brightness during the early observations. However, it doesn’t explain what happened after the explosion that made the star disappear. One explanation could be that it faded a lot after its outburst, and was then hidden by a dense cloud of cosmic dust. If that were the case, the objects could reappear in further observations. 

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