A team from Caltech has possibly identified the first-ever superkilonova, an extraordinary cosmic event where a star explodes in two very different ways. This exciting discovery started with gravitational wave observations detected earlier in the year.
Supernovas happen when massive stars collapse and explode, often leaving behind a neutron star. Kilonovas, on the other hand, result from two neutron stars merging, causing powerful gravitational waves that ripple through the universe. These waves are akin to ringing a cosmic bell.
On August 18, 2025, the LIGO-Virgo-KAGRA collaboration detected gravitational waves. Astronomers quickly sprang into action, searching for the source. They found a rapidly fading object 1.3 billion light-years away, named AT2025ulz.
This event shares similarities with the confirmed kilonova GW170817 from 2017. That discovery marked a major breakthrough, as it was the first time scientists pinpointed the origin of gravitational waves. Like GW170817, the remnants observed in AT2025ulz emitted a red glow due to heavy elements like gold being formed after an energetic collision. But then, to everyone’s surprise, AT2025ulz brightened again, showing characteristics typical of a supernova.
So, what exactly is AT2025ulz—a supernova or a kilonova? Researchers propose it’s both. Past research has theorized that supernovae can occasionally produce two neutron stars instead of one. If these stars collide immediately, it could create the gravitational waves of a kilonova.
Usually, mergers happen far away in space, giving scientists a clear view of their emissions. However, Brian Metzger, an astronomer involved in the study, pointed out that the recent collision occurred within the exploding star, obscuring the kilonova signals behind the mass of ejected material.
Another intriguing aspect is that one of the colliding objects was surprisingly small—smaller than a typical neutron star. This finding challenges existing theories about how neutron stars form and adds depth to our understanding of stellar evolution. Metzger explained that this could happen if a rapidly spinning massive star fragments into two low-mass neutron stars.
In the future, researchers hope to gather more evidence to confirm the existence of superkilonovas. The study also serves as a reminder of the universe’s complexity. As Mansi Kasliwal from Caltech stated, future kilonova events might not resemble past observations and could be misidentified as supernovae.
This research highlights the mysteries of our universe and indicates that there’s much more to learn. You can read the full study published in The Astrophysical Journal Letters here.
The landscape of astronomy is always evolving, and these findings will surely encourage more discussions in scientific circles and social media. Questions about how stellar processes work continue to engage both experts and enthusiasts alike.
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