Astronomers have made a remarkable discovery about Sakurai’s Object, one of the fastest-changing stars ever observed. New observations show that this unusual star has entered a fresh stage of its evolution, giving scientists a rare chance to watch the dramatic life cycle of a dying star unfold over just a few decades.
Normally, stars change incredibly slowly. Major stages of stellar evolution can take thousands, millions, or even billions of years. But Sakurai’s Object is different. Its rapid transformation allows astronomers to study stellar evolution almost as if they were watching it happen in real time.
Researchers from The University of Manchester, the Valongo Observatory, and other institutions used the European Southern Observatory’s Very Large Telescope (VLT) in Chile to investigate the star’s current condition. Their findings, published in Monthly Notices of the Royal Astronomical Society, reveal that Sakurai’s Object is now developing a powerful stellar wind similar to those seen in Wolf-Rayet stars.
A Star That Was Already Near the End
Sakurai’s Object is believed to have once been similar to our Sun. Like the Sun, it was an ordinary star that spent most of its life producing energy through nuclear fusion.
However, the star eventually ran out of the fuel needed to continue normal nuclear burning. It then moved toward the final stages of its evolution, leaving behind a hot and extremely dense core that would eventually become a white dwarf.
At this point, Sakurai’s Object should have continued quietly fading into its final stage.
Instead, something extraordinary happened.
In 1996, the star suddenly became much brighter and began changing dramatically.
Scientists believe this happened because of an extremely rare event called a very late thermal pulse.
The Star Suddenly Came Back to Life
A very late thermal pulse occurs when a layer of helium deep inside an already dying star suddenly reignites.
This renewed burst of nuclear activity can cause the star to expand rapidly. As it expands, its surface becomes cooler, while enormous amounts of gas and dust can be thrown into surrounding space.
For a short period, the star effectively appears to return to an earlier stage of its life.
Because of this extraordinary behavior, astronomers describe Sakurai’s Object as a “born-again” star.
Only two stars have been directly observed experiencing this kind of dramatic rebirth: Sakurai’s Object and V605 Aquilae.
That makes Sakurai’s Object an exceptionally valuable target for astronomers.
Why Watching It Change Matters
Professor Albert Zijlstra from the Jodrell Bank Center for Astrophysics at The University of Manchester explained that most stars evolve far too slowly for humans to observe major changes during a lifetime.
Astronomers therefore normally have to study many different stars and compare them with one another. By examining stars at different stages, they can reconstruct how stellar evolution works.
Sakurai’s Object provides something much rarer.
Scientists can observe the same star changing significantly over only a few decades.
This gives researchers an opportunity to test computer models and theories of stellar evolution against real observations.
It is particularly important because the stage Sakurai’s Object is going through is relatively short and not yet fully understood.
Hidden Behind Dust and Gas
There is one major challenge.
After its 1996 eruption, Sakurai’s Object released large quantities of material into space. The gas and dust surrounding the star became so thick that the star was largely hidden from direct observation.
Astronomers therefore needed to study the light that could still be detected and use advanced models to understand what was happening behind the dusty cloud.
The research team used observations from the Very Large Telescope, one of the world's most powerful ground-based astronomical facilities.
They examined the star’s light and compared the observations with detailed computer models designed to simulate stellar atmospheres and powerful stellar winds.
The results revealed clear signatures of carbon and helium in the star’s environment.
These clues allowed the researchers to estimate the star’s temperature, chemical composition and the properties of its stellar wind.
The Star Is Heating Up Again
One of the most interesting findings is Sakurai’s Object’s current temperature.
The researchers estimate that its surface temperature is now between approximately 27,000 and 36,000 kelvin, equivalent to roughly 48,000–64,000°F.
That is extremely hot.
More importantly, the measurements show that the star is reheating after its dramatic eruption nearly three decades ago.
The star is therefore continuing its journey through a very unusual stage of stellar evolution.
The new observations also show that Sakurai’s Object has developed a powerful stellar wind with characteristics associated with Wolf-Rayet stars.
Wolf-Rayet stars are known for their extremely strong winds, which can remove enormous amounts of material from their surfaces.
Reheating More Slowly Than Expected
The researchers also discovered something that could change how scientists understand these “born-again” stars.
Earlier models predicted that Sakurai’s Object might reheat at a different rate. However, the new measurements suggest that its reheating is happening more gradually than some models predicted.
This difference is scientifically important.
Computer simulations are based on theories about how matter behaves inside dying stars. By comparing predictions with observations of Sakurai’s Object, astronomers can determine which models better explain what actually happens.
Professor Zijlstra said that monitoring the star in the coming years should provide even more information about this unusual phase.
Every new observation could reveal another step in the star’s rapid transformation.
Younger Than Another Born-Again Star
The research also provides an interesting comparison with V605 Aquilae, the other star known to have experienced a similar event.
V605 Aquilae underwent its dramatic transformation around 80 years ago. Based on their observations, scientists believe Sakurai’s Object is currently at an earlier stage of its evolution than V605 Aquilae.
Studying both objects could therefore help astronomers understand how a born-again star changes over time.
It is like having two natural experiments occurring at slightly different points in the same extraordinary process.
A Rare Window Into a Star’s Final Moments
Sakurai’s Object is much more than an unusual star. It is a natural laboratory for studying how stars die.
Stars like our Sun are expected to eventually exhaust their nuclear fuel, shed their outer material and leave behind white dwarfs. But the final stages of this process can involve complicated and poorly understood events.
Because most of these changes happen far too slowly for humans to witness, astronomers usually depend on observations of different stars and theoretical calculations.
Sakurai’s Object gives scientists something special: a dying star changing on a human timescale.
Its transformation began dramatically in the 1990s, and astronomers are still able to follow its evolution today.
As the star continues to heat up and evolve, researchers plan to observe it closely in the coming years. These observations could help explain how stars transition through their final stages and eventually complete their journey toward becoming white dwarfs.
For astronomy, Sakurai’s Object offers a rare opportunity to witness something normally hidden from human eyes: the evolution of a star unfolding almost in real time.
Reference: W Marcolino, P A M van Hoof, V C Maria, H Todt, G C Van de Steene, J A Toalá, S Kimeswenger, M Hajduk, J -C Bouret, D Tafoya, D Barría, A A Zijlstra, The emergence of a [WC] star in Sakurai’s object, Monthly Notices of the Royal Astronomical Society, Volume 552, Issue 1, October 2026, stag1533, https://doi.org/10.1093/mnras/stag1533
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