A strange chirp in the light of an exploding star has given astronomers the first direct evidence of a magnetar being born. The discovery, made by researchers in the United States, confirms that these ultra magnetic neutron stars can power the brightest supernovae in the universe. It also marks the first time Einstein's general relativity has been used to explain the mechanics of a supernova.
A 16 year old theory finally proven
Superluminous supernovae shine 10 times brighter than ordinary stellar explosions. Since astronomers first spotted them in the early 2000s, they could not explain why these blasts stay so bright long after a star's core collapses. In 2010, UC Berkeley theoretical astrophysicist Dan Kasen proposed an answer: a newborn magnetar. He argued that when a massive star dies, its core can collapse into a neutron star instead of a black hole. If the original star had a strong magnetic field, the collapse would amplify it, creating a magnetar with a magnetic field 100 to 1,000 times stronger than a typical pulsar. Young magnetars can spin more than 1,000 times per second. As they rotate, their magnetic fields accelerate charged particles that slam into the supernova debris, injecting extra energy and keeping the explosion bright.
A chirp in the light curve
Graduate student Joseph Farah of UC Santa Barbara and Las Cumbres Observatory found the strongest evidence yet for this theory. He studied a supernova discovered in 2024 called SN 2024afav. Farah and his colleagues noticed unusual bumps in the supernova's light curve. These bumps, which they described as a chirp, can only be explained using Einstein's theory of general relativity. The chirp revealed that a newborn magnetar was wobbling, or precessing, as it spun. This wobble, caused by the effects of general relativity, injected extra energy into the expanding debris, making the supernova shine far longer than normal.
Why this matters to the people who study the sky
For astronomers, this is the first direct observation of a magnetar's birth. It confirms that these exotic objects are real and that they power the universe's brightest explosions. The discovery also validates a theory first proposed 16 years ago and shows that general relativity can be used to understand supernova mechanics. Magnetars are also believed to generate mysterious fast radio bursts, so understanding their birth could help explain those signals too. The research was published in the journal Nature.
