An alert from a space telescope led to observations across several continents. From its position in the Northern Cape Karoo, SALT contributed an important part of the record of a star’s final explosion.
The powerful telescope outside Sutherland has helped astronomers study the explosive death of a massive star about 500 million light years from Earth.
The Southern African Large Telescope, better known as SALT, collected information over almost two months as scientists investigated one of the earliest stages of a supernova ever observed.
The event has given researchers a rare view of what happens when a massive star reaches the end of its life, while raising new questions about why apparently similar stars can die in different ways.
A brief flash in space
The first sign of the explosion was detected on 21 March 2026 by the Einstein Probe, an X-ray space telescope led by the Chinese Academy of Sciences. The telescope recorded a short burst of low-energy X-rays coming from a distant galaxy. Within an hour, observatories around the world had begun pointing their instruments towards the source.
Follow-up observations revealed a rapidly brightening supernova, which was later named SN 2026gzf.
A supernova occurs when a star explodes. In this case, the star was about 30 times the mass of the Sun and had already lost its outer layers of hydrogen and helium before it died.
Scientists classified the explosion as a broad-lined Type Ic supernova. These are unusually energetic events that send material into space at extremely high speeds. The initial X-ray flash was identified as a “shock breakout”. This happens when the core of a massive star collapses and triggers a powerful shock wave. As the shock wave reaches the star’s surface, it releases a sudden burst of X-ray and ultraviolet radiation.
Astronomers believe shock breakouts occur at the beginning of most supernovae. They are seldom detected, however, because they last for such a short time and scientists must happen to be watching the right area of space at the right moment.
This was the first shock breakout to be observed clearly since 2008.
SALT joins the investigation
Once the alert was issued, telescopes in several countries began monitoring the explosion at different wavelengths. SALT, located at the South African Astronomical Observatory near Sutherland, gathered eight spectra of the supernova over almost two months.
A spectrum is produced when light from an object is separated into its different wavelengths. By studying these patterns, astronomers can identify the elements present in an exploding star. They can also measure temperature and other physical changes that can't be determined from an ordinary image alone.
SALT’s observations helped scientists follow the development of the supernova after its initial X-ray flash. Other observations came from optical, radio and X-ray telescopes in Chile, Germany and the United States, along with instruments operating in space.
The data allowed researchers to study the supernova itself and the way the explosion interacted with material the star had released before its death. This surrounding material provided clues about the star’s final years. Researchers found evidence that it had become increasingly unstable before collapsing, releasing matter into the space around it.
The missing gamma-ray burst
The explosion was also unusual for something it did not produce. Broad-lined Type Ic supernovae are often associated with gamma-ray bursts. These are extremely powerful flashes created when narrow jets of material travel outwards at speeds close to the speed of light.
SN 2026gzf displayed many of the characteristics normally associated with these events, but astronomers found no gamma-ray burst. They also found no evidence of a successful high-speed jet or the afterglow such a jet would usually leave behind.
One possible explanation is that the star did produce a jet, but that it was unable to break through the star’s surface or the dense material surrounding it. Scientists refer to this as a “choked jet”.
The existence of choked jets has been proposed for decades, but they have proved difficult to identify conclusively.
The findings suggest that massive stars might have a wider range of possible endings than scientists previously understood. Two stars with apparently similar characteristics might collapse in different ways, with one producing a gamma-ray burst while another does not. Researchers hope that studying SN 2026gzf will help them understand what determines whether a jet escapes.
International science from the Karoo
SALT is the largest single optical telescope in the Southern Hemisphere. Its position near Sutherland gives it access to dark skies with little artificial light, making the Karoo an important base for international astronomy.
The telescope did not detect the first X-ray flash itself. That discovery was made from space. SALT's role was to help track and analyse what followed, adding detailed information about the changing light from the supernova. The research shows how modern astronomy relies on cooperation between different observatories. No single telescope could collect all the information needed to understand an event of this kind.
In this case, an alert from a space telescope led to observations across several continents. From its position in the Northern Cape Karoo, SALT contributed an important part of the record of a star’s final explosion.
Anchen Coetzee
Mariana Balt
Lynette Spencer
Liz Thorne
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