Scientists discover a ‘forbidden’ pulsar fleeing a supernova in a seemingly empty region of the Milky Way

From supermassive black holes to vast stellar nurseries, the distant reaches of space are full of many baffling wonders.

Now, scientists have uncovered one of the most perplexing mysteries yet.

Astronomers have spotted a runaway pulsar, known as Calvera, fleeing the aftermath of a massive stellar supernova explosion.

What makes this truly extraordinary is that this system should be ‘forbidden’ in this empty region of the galaxy, 6,500 light–years above the plane of the Milky Way.

Pulsars are the ultra–dense cores left behind when supermassive stars collapse and explode into supernovae at the end of their lives.

However, the massive stars that birth pulsars shouldn’t be able to form so far from dense regions of gas and dust near the galactic plane.

Lead researcher Dr Emanuele Greco, of Italy’s National Institute for Astrophysics, told Daily Mail: ‘Since a pulsar is the compact leftover of the explosion of a massive star, it is surprising to see it very far away from the galactic disk.

‘It means that during its normal life as a star, it ran away from the disk and then exploded.’

Scientists have discovered a ‘forbidden’ pulsar (left), named Calvera, rapidly fleeing a stellar supernova explosion (right) in an otherwise empty region of the Milky Way 

Located 6,500 light–years above the plane of the Milky Way, there shouldn’t have been enough matter to create a star big enough to birth a pulsar in the Calvera system (pictured)

The Calvera system, named after the villain from the movie ‘The Magnificent Seven’, was spotted in 2022 by the Low Frequency Array (LFR) radio telescope.

Calvera immediately grabbed scientists’ attention since it didn’t seem to fit with any of the rules of star formation.

High above the disc of the Milky Way, the dust and gas thins out and enormous regions are dominated by the void between stars.

However, the LFR, which is spread over eight European countries, detected a near–perfectly circular region which astronomers identified as the remains of a supernova.

At the end of a star’s life, when it has burned through all of its fuel, the outermost layers will collapse inwards under gravity and generate enormous amounts of pressure.

If the star is big enough, that pressure will trigger a colossal explosion known as a supernova, which leaves behind an expanding sphere of dust and gas.

This explosion also leaves behind a compact object in the form of a neutron star or even a black hole.

Pulsars are a type of rapidly spinning neutron star that rotates up to 700 times a second, producing a flashing signal as its beam of radiation sweeps through the galaxy.

Pulsars are rapidly spinning neutron stars, formed by supernova explosions. Using new measurements, scientists have found that the Calvera pulsar was ejected from the supernova remnant by the force of the explosion 10,000–20,000 years ago (stock image) 

Dr Greco says: ‘During the explosion of a star, the pulsar feels a kick in the direction opposite to the one in which the stellar fragments are mainly ejected. You can basically see it as a recoil of the explosion.’

In the Calvera system, astronomers detected both a supernova remnant and a powerful pulsar, which appeared to be shooting out into space away from the blast.

To learn more, Dr Greco and his co–authors combined X–ray data from the European Space Agency’s XMM–Newton Spacecraft with measurements from other telescopes across the electromagnetic spectrum.

This revealed that the supernova remnant is between 13,000 and 16,500 light–years from Earth.

‘What is even more surprising is that we still see the diffuse remnant of the explosion, which last for relatively short periods – a few dozen thousand years at max – with respect to the life of a star, meaning that the explosion occurred relatively recently,’ says Dr Greco.

Based on their data, the researchers say that the supernova likely occurred between 10,000 and 20,000 years ago.

While the Calvera pulsar will keep spinning for millions of years to come, the supernova remnant will likely vanish in ‘about a few thousand years’.

Dr Greco adds: ‘Our study shows that even the quietest and seemingly empty regions of the galaxy can harbour extreme processes.’