The missing star was an unstable massive white dwarf located some 75 million light-years from Earth. Astronomers behind the European Southern Observatory’s (ESO) Very Large Telescope (VLT) in Chile are now trying to crack the mystery of its disappearance. The star was first studied between 2001 and 2011 when astronomers determined it was a white dwarf at a late stage of its evolutionary cycle.
Researchers have now proposed the star may have dimmed and became obscured by clouds of stellar dust.
A more exciting theory suggests the white dwarf has collapsed in on itself, forming a black hole.
According to PhD candidate and study leader Andrew Allan of Trinity College Dublin, Ireland, this could be the first-ever observation of its kind.
Mr Allan said: “If true, this would be the first direct detection of such a monster star ending its life in this manner.”
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The white dwarf was located in the Kinman Dwarf galaxy, in the constellation Aquarius.
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.
Astronomers can, however, detect the signatures coming from the galaxy.
Between 2001 and 2011, they found evidence of a “luminous blue variable star” about 2.5 million times brighter than our Sun.
Stars of this type are known for being unstable and will occasionally shift in brightness and spectra.
We were surprised to find out that the star had disappeared
Andrew Allan, Trinity College Dublin
But by 2019, the star’s characteristic emissions were absent from collected data sets, suggesting it has disappeared.
When the researchers pointed the VLT directly at the galaxy, the star’s signatures where nowhere to be seen.
Mr Allan said: “Instead, we were surprised to find out that the star had disappeared!”
He added: “It would be highly unusual for such a massive star to disappear without producing a bright supernova explosion.”
White dwarf stars are the exposed cores of stars that have run out of nuclear fuel.
When a star reaches the end of its life, it will expand its outer material, leaving behind an incredibly dense and hot core.
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According to NASA, a typical white dwarf is about half as massive as the Sun but only slightly bigger than the Earth.
Jose Groh, of Trinity College Dublin, said: “We may have detected one of the most massive stars of the local Universe going gently into the night.
“Our discovery would not have been made without using the powerful ESO eight-metre telescopes, their unique instrumentation, and the prompt access to those capabilities following the recent agreement of Ireland to join ESO.”
By analysing past data, the astronomers have found the star may have been going through a period of strong outbursts sometime after 2011.
The outbursts may have caused the star to morph into a less luminous one.
Throwing a cloud of stellar dust into the equation could explain why the star vanished without producing a supernova.
Alternatively, the star may have collapsed into a black hole without exploding into a supernova.
The second scenario would be incredibly rare as most massive stars appear to end their lives in these monstrous cosmic explosions.
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