A brightly burning ‘zombie’ supernova that refuses to die has left astronomers baffled.
The star, which lies half a billion light years away, has exploded numerous times since 1954.
This has stumped astronomers as supernovas are generally considered to explode just once and standard theoretical models cannot explain its behaviour.
A brightly burning ‘zombie’ supernova that refuses to die has left astronomers baffled. The star, which lies half a billion light years away, has exploded numerous times since 1954.
Researchers at Las Cumbres Observatory in Goleta, California, have been studying the phenomenon, which was first observed in 2014 by the Intermediate Palomar Transient Factory telescope near San Diego.
In January 2015 the event, known as iPTF14hls, was classified as a type II-P supernova, which results from the rapid collapse and violent explosion of a single massive star.
This type of supernova gives off a distinctive flash and tend to stay bright for around 100 days and supernovae lasting more than 130 days are extremely rare.
But iPTF14hls remained bright for almost two years (600 days), with the brightness of the light it emitted varying by up to 50 per cent over this time, as if it were exploding over and over again.
The evolution of the event also seems to be taking place roughly ten times slower than others of its type.
Adding to the puzzle, telescope imagery uncovered by the team suggests explosions may have taken place at the same location in 1954.
Supernovae are known to explode only once, shine for a few months and then fade, but iPTF14hls experienced at least two explosions, 60 years apart
Writing in an opinion piece for the journal Nature, Stan Woosley, a professor of astronomy at the University of California, Santa Cruz, said of the findings: ‘As of now, no detailed model has been published that can explain the observed emission and constant temperature of iPTF14hls, let alone the possible eruption 60 years before the supernova.
A brightly burning supernova that appears to defy the laws of physics has left astronomers baffled. Unlike similar supernovae, which stay bright for around 100 days, the event known as iPTF14hls remained bright for more than 600 days
Researchers, including lead author Iair Arcavi (foreground), at Las Cumbres Observatory in Goleta, California, have been studying the mysterious phenomenon ever since. Their observations include data from Keck Observatory on Maunakea, Hawaii (background)
‘A better understanding could provide insight into the evolution of the most massive stars, the production of the brightest supernovae and possibly the birth of black holes that have masses near 40 solar masses, such as those associated with the first direct detection of gravitational waves.
‘For now, the supernova offers astronomers their greatest thrill: something they do not understand.’
One explanation offered by the researchers for the unusual activity of iPTF14hls could be to do with its size.
Adding to the puzzle, telescope imagery uncovered by the team suggests explosions may have taken place at the same location before. An image taken by the Palomar Observatory Sky Survey reveals a possible explosion in the year 1954 at the location of iPTF14hls
The explosion is not seen in a later image taken in 1993. Supernovae are known to explode only once, shine for a few months and then fade, but iPTF14hls experienced at least two explosions, 60 years apart
They suggest that the star had an initial mass 95 to 130 times that of the sun.
This could be enough to fuel an ongoing series of explosions, rather than one final death blow.
Under this model, the star would give off supernovae like signals, without destroying the star itself.
But without a concrete explanation, scientists may be forced to rethink their current understanding of supernovae behaviour.
The full findings were published in the journal Nature.