Scientists Solve Mystery Behind Ultra-Bright Star Explosions

Researchers have discovered what makes some stellar explosions shine 10 to 100 times brighter than typical supernovas. The answer lies in magnetars - rapidly spinning stellar remnants with powerful magnetic fields that supercharge the explosion's brightness.

Scientists have cracked the code on one of space’s most puzzling phenomena – why certain stellar explosions shine with extraordinary brilliance that dwarfs even the most spectacular cosmic events.

When massive stars reach the end of their lives, they explode in what astronomers call supernovas. These cosmic blasts typically outshine our sun by about a billion times. However, a rare subset of these explosions – dubbed superluminous supernovas – blazes 10 to 100 times brighter than even these already incredible displays.

The mystery behind these ultra-bright explosions has now been solved thanks to observations of a superluminous supernova discovered in December 2024, located in a galaxy roughly one billion light-years away from Earth. Scientists used telescopes from the Las Cumbres Observatory in California and Chile’s ATLAS survey to study the phenomenon.

The research team found that these exceptionally bright explosions occur when the stellar blast creates a magnetar – an incredibly dense, fast-spinning remnant of the original star with an extraordinarily strong magnetic field. This magnetar acts like a cosmic engine, gathering charged particles as it rotates hundreds of times each second and hurling them into the expanding cloud of stellar debris.

Joseph Farah, a doctoral student in astrophysics at Las Cumbres Observatory and UC Santa Barbara who led the study published Wednesday in Nature journal, explained the process behind magnetar formation.

“When a massive star exhausts its nuclear fuel, it can no longer resist the crushing force of gravity,” Farah said. “The core of the star is squeezed under the weight of the entire star above it, crushing it so hard that protons and electrons merge to form neutrons. If the mass of the core is too large, it will just collapse into (forming) a black hole. But if the conditions are right, the nascent neutron star will survive the core collapse.”

The magnetar remains concealed within the supernova’s center, driving its incredible luminosity from inside the explosion.

This discovery builds on earlier work by Las Cumbres Observatory scientist Andy Howell, who first identified a superluminous supernova in 2006. A theory suggesting magnetars might power these ultra-bright explosions was put forward in 2010, and Howell, who co-authored the current study, believes these new findings validate that hypothesis.

Unlike regular supernovas that follow predictable brightness patterns, some superluminous supernovas like this one show fluctuating brightness over several months. The team noticed these brightness variations become increasingly frequent over time.

The scientists traced this pattern to a phenomenon called Lense-Thirring precession, where the spinning magnetar actually warps the fabric of space-time around it. Following the explosion, the magnetar’s gravitational pull draws in some stellar material, creating a disk that wobbles due to this space-time distortion.

“This causes the transfer of the energy from the magnetar to the newly expanding supernova to vary,” creating the brightness fluctuations, Howell explained.

While researchers haven’t pinpointed the exact size of the original star, they believe it was enormous.

“We don’t know a lot about the star that exploded, but it was likely a very massive star” that was many dozens of times more massive and hundreds of thousands of times more luminous than our sun, Farah noted.

To put the incredible brightness of these explosions in perspective, Farah offered a striking comparison.

“There’s a great ‘what if’ that asks: what would be brighter, the sun going supernova 93 million miles (150 million km) from Earth,” he said, referencing the distance between Earth and the sun, “or a hydrogen bomb detonating on your eyeball? And the answer is the supernova – by nine orders of magnitude.”

“So that’s just a regular supernova. A superluminous supernova is 10 to a hundred – or more – times brighter than that. In absolute terms, our supernova had a luminosity brighter than the output of the entire Milky Way galaxy combined,” Farah added.