Astronomers have spotted 72 extremely bright and quick events flashing in the sky – and they have no idea what they are. The mysterious explosions are similar in brightness to supernovae, which are the gigantic explosions of dying stars. But supernovae can be seen lighting up the sky for months at a time.
However, the latest 72 mysterious explosions 4 billion light years away can only be seen from a week to a month. The most recent signals span up to one hundred times the distance from the Earth to the sun in size (around 9,300 miles/ 15,000 million kilometres), researchers believe. While astronomers still aren’t sure exactly what it is, they have a few theories. One is that it could be a never-before-seen type of supernova in which a star sheds a huge amount of material before it explodes.
Pictured are images of one of the baffling events, from eight days before the maximum brightness (top left) to 18 days afterwards (bottom right). This outburst took place at a distance of 4 billion light years
This latest strange deep-space signal was spotted using a large camera on a 4-metre telescope in the Cerro Tololo Inter-American Observatory (CTIO) in the Chilean Andes. The explosions come from around 4 billion light years away, but astronomers have no idea exactly what is producing them. They are believed to be incredibly hot, releasing heat from 10,000 to 30,000 degrees Celsius (around 18,000 to 54,000 degrees Fahrenheit), researchers found.
Miika Pursiainen of the University of Southampton, who is leading the Dark Energy Survey Supernova Programme (DES-SN), presented the findings at the European Week of Astronomy and Space Science in Liverpool.
Graph showing the evolution of brightness for two quick transient events (discussed in the most recent findings) and two typical supernovae. The rapid events (pictured in yellow) are visible for less time, from a week to a month, whereas sypernovae last for several months or more (pictured in red and purple)
“They are as bright as supernovae but last for significantly shorter periods of time. Next to that, they seemed to be both hot and large and appeared to expand in time”, Dr Pursiainen told Newsweek. “These events appear to originate in star-forming galaxies, which is why we have been mostly considering core-collapse supernova scenarios. However, it is far too early to say anything for certain.”
One possibility is that the star sheds a lot of material before a supernova explosion. In extreme cases, the supernova may itself then heat up the surrounding material to very high temperatures.
This means these lights could be the hot cloud rather than the exploding star itself. Another possibility is that astronomers are seeing a newly discovered supernova in action. The team will need a lot more data to work out if this is what is happening or not.
“The DES-SN survey is there to help us understand dark energy, itself entirely unexplained”. That survey then also reveals many more unexplained transients than seen before, Dr Pursiainen said. “If nothing else, our work confirms that astrophysics and cosmology are still sciences with a lot of unanswered questions!”