- A star in the dwarf galaxy PHL 293B has disappeared without a trace.
- The ginormous star, a type of luminous blue variable star, shined between 2.5 and 3.5 times brighter than our sun.
- Astronomers suspect it may be a case of supernova gone wrong.
A stellar whodunnit is afoot 75 million light-years from Earth. Astronomers had been observing a distant dwarf galaxy called PHL 293B when a star 2.5 million times brighter than our sun suddenly disappeared.
It’s possible the star collapsed into a black hole without going full supernova first. “If true,” astrophysicist Andrew Allan of Trinity College Dublin in Ireland said in a statement, “this would be the first direct detection of such a monster star ending its life in this manner.”
Typically, at the end of a star’s life, it will go supernova before turning into either a black hole or neutron star. This violent stage is hard to miss and can last for years. Astronomers likely would have caught sight of the explosion.
The missing star is a strange type of star called a luminous blue variable. These bizarre, hulking stars are marked by violent outbursts, during which they shine twice as bright as before. Luminous blue variable stars are known for being highly erratic, and they vary greatly in their spectra and luminosity.
Astronomers observed the luminous blue variable star frequently between 2001 and 2011, but when they trained the European Southern Observatory’s Very Large Telescope in Chile on the PHL 293B galaxy in 2019, the star had simply disappeared. A review of data collected between 2011 and 2016 revealed that it wasn’t visible after 2011. The scientists published the puzzling data earlier this month in the Monthly Notices of the Royal Astronomical Society.
According to some models, the luminous blue variable star might have skipped the supernova stage and formed a slow-spinning black hole instead, Allan told Gizmodo. This scenario would reshape what we think about how stars live and die.
Another prime suspect? Dust. Allan and his team have also suggested the star may have have been shrouded in a thick fog of gas and dust, obscuring it from view. Near-infrared observations taken in 2009 suggest this cloud of gas and dust would need to be extremely cold in order to shade the star undetected.
This isn’t the first time a star has completely vanished without a trace. In 2017, astronomers were stunned when a red giant star 22 million light-years away in the Fireworks Galaxy suddenly disappeared. At the time, they chalked it up to a supernova gone wrong.
Only time and more observations will reveal what actually happened to this star. For now, the cosmic mystery remains unsolved.