Astronomers baffled over 72 ‘extremely bright’ explosions

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.

Highlights:

• Scientists who observed this strange event are trying to understand dark energy
• They are looking for supernovae - the explosion of stars at the end of their lives
• The mysterious explosions are similar in brightness to supernovae, but they don't last as long

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.

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.

'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. 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. 'These events appear to originate in star-forming galaxies, which is why we have been mostly considering core-collapse supernova scenarios,' he said.

'However, it is far too early to say anything for certain', he said. 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!' he said. Mysterious signals coming from distant galaxies could be evidence of deep-space explorers billions of light-years from Earth, a recent study has claimed.

Researchers from the Harvard-Smithsonian Center for Astrophysics in March 2017 claimed a solar-powered transmitter using sunlight cast on an area twice the size of Earth could generate enough energy to be 'seen' by far away viewers.And, a water-cooling system would allow a device of this size to withstand the extreme heat.

The researchers argue that the most plausible use for this tremendous amount of power would be to drive interstellar light sails. The light sail would rely on a steady beam from the transmitter. While this would always be pointed at the sail, observers on Earth would see it as a brief flash, as the sail, its host planet, its star, and the galaxy all move relative to us. This would cause the beam to sweep across the sky, only pointing at Earth for a moment.

What is a supernova and how does it form?

A supernova occurs when a star explodes, shooting debris and particles into space. A supernova burns for only a short period of time, but it can tell scientists a lot about how the universe began.

One kind of supernova has shown scientists that we live in an expanding universe, one that is growing at an ever increasing rate.Scientists have also determined that supernovas play a key role in distributing elements throughout the universe.