A team of astronomers has confirmed the discovery of a superluminous supernova, designated SN Winny, whose light has been split into five distinct images by gravitational lensing. The researchers, from the Technical University of Munich, Ludwig Maximilian University of Munich, and the Max Planck Institutes, spent six years searching for such an event.
They calculated the probability of this specific alignment at less than one in a million. SN Winny is located approximately 10 billion light-years from Earth. Between the supernova and our planet lie two massive foreground galaxies.
Their combined gravity warps spacetime, creating a cosmic lens that bends the supernova’s light along multiple paths. Because each path has a slightly different length, the same explosion reaches Earth not as a single flash, but as five separate images arriving at different times.
The astronomers describe these images as five echoes of a single stellar death. The discovery holds particular significance for cosmology due to a persistent problem known as the Hubble tension. The Hubble constant measures the rate at which the universe is expanding. Two established methods for calculating this constant produce conflicting results.
One method, based on observations of the early universe, yields one value. The other method, based on observations of nearby stars and galaxies, yields a different value.
Neither approach has been able to reconcile the discrepancy, making it one of the most stubborn puzzles in modern cosmology. SN Winny offers a third, independent route to measuring the Hubble constant. By precisely measuring the time delays between the arrival of each of the five images, scientists can calculate the expansion rate.
The principle is straightforward: longer delays indicate greater stretching of light by the expansion of space. The geometry of the lensing galaxies is already known.
With the time delays plugged in, the calculation can produce a number. If that number matches one of the existing methods, the Hubble tension would be resolved. If it matches the other, the mystery would deepen.
Either outcome would provide a critical data point that cannot be ignored. The supernova itself is extraordinary.
A superluminous supernova is already rare. One that is also gravitationally lensed into multiple images is exceptionally rare. The alignment required—Earth, the two foreground galaxies, and the distant explosion in a near-perfect straight line—is the kind of cosmic accident that astronomers typically only hope to find.
The team did not stumble upon SN Winny. They conducted a systematic search over six years, looking for a needle in a haystack the size of the observable universe.
Time is now a critical factor. The time delays between the five images are finite. The supernova will fade, and the echoes will cease.
The window for measuring those delays with precision is limited. The research team is racing to gather the necessary data before the light goes dark.
If they succeed, the payoff will be a new, independent measurement of the universe’s expansion rate. That measurement could settle a long-standing dispute or deepen the mystery. Either way, it will come from a single star that died 10 billion years ago, whose death cry reached Earth in five separate waves.
