Webb Telescope detects what could be the earliest supernova in the observable universe

 

Astronomers have recently found the oldest supernova known so far. Called GRB 250314A, this old star erupted during an era when the universe was still stabilizing.

Shortly after the initial galaxies illuminated the darkness, a colossal object collapsed, detonated, and emitted its light, which traveled through space for billions of years before finally arriving here.

That illumination didn't come in a tidy, straightforward form. It emerged initially as a brief, fierce flash, then subsequently as a gradual, expanding radiance.

Combined, those signals enabled researchers to detect the oldest supernova of its kind ever observed, aided by the precise observations of NASA’s James Webb Space Telescope (JWST).

Supernova GRB 250314A

NASA reports that Webb detected a supernova that erupted when the universe was just 730 million years old, marking it as the earliest observation of its type thus far.

Webb's near-infrared images were clear enough to identify the faint host galaxy of the supernova as well.

The telescope conducted these quick observations on July 1 after a global network of telescopes detected a strong flash known as a gamma-ray burst in mid-March.

This new detection also exceeds Webb’s previous record. Prior to this, the farthest supernova that Webb had analyzed directly originated from a star that detonated when the universe was roughly 1.8 billion years old.

The researchers were not merely interested in knowing that something luminous occurred. They aimed to demonstrate what it was. That's where the sensitivity of Webb was significant.

Andrew Levan, the primary author of one of two recent articles in Astronomy and Astrophysics Letters, is a professor at Radboud University located in Nijmegen, the Netherlands.

“Only Webb has the ability to directly demonstrate that this light originates from a supernova – a massive star that is collapsing,” stated Levan. “This finding also shows that we can utilize Webb to identify individual stars when the universe was merely five percent of its present age.”

“Webb delivered the quick and precise follow-up we required,” stated Benjamin Schneider, a co-author and a postdoctoral researcher at the Laboratoire d’Astrophysique de Marseille in France.

After a strong cosmic explosion

Gamma-ray bursts rank among the most intense occurrences that researchers can observe. Most last from seconds to minutes, and they’re so rare that each can seem like a once-in-a-career notification.

Brief eruptions can result from collisions between neutron stars and black holes. Lengthier events, like this one that persisted for about 10 seconds, are frequently associated with the demise of massive stars.

In this instance, the initial alert was issued on March 14. The SVOM mission, a Franco-Chinese telescope initiated in 2024 to detect brief celestial occurrences, identified the gamma-ray burst.

In approximately an hour and a half, NASA’s Neil Gehrels Swift Observatory accurately identified the X-ray position in the sky, preparing for the following series of observations.

Approximately 11 hours following the initial alert, the Nordic Optical Telescope located in the Canary Islands detected an infrared afterglow. Four hours later, the Very Large Telescope of the European Southern Observatory in Chile estimated that the source originated roughly 730 million years following the big bang.

“According to Levan, only a few gamma-ray bursts have been observed in the universe's first billion years over the past 50 years.” “This specific occurrence is extremely unusual and quite thrilling.”

This bright star seemed recognizable.

A supernova from such an early point in cosmic history might appear unusual. Ultimately, the initial billion years were distinct.

Early stars probably contained a smaller quantity of heavy elements. They could have been larger and had briefer lifespans. This period coincided with the Era of Reionization, during which gas between galaxies was better at obstructing high-energy radiation.

The team contrasted their observations with supernovae nearer to Earth, where astronomers possess decades of comprehensive data. The unexpected aspect was how ordinary it appeared.

“We approached it with open minds,” remarked Nial Tanvir, a co-author and professor at the University of Leicester in the UK. “Indeed, Webb demonstrated that this supernova appears just like contemporary supernovae.”

That doesn’t imply everything is the same. It refers to the general outline of the event, how it illuminated and diminished, and the hints in its brightness correspond to patterns that astronomers are familiar with.

The subsequent step involves identifying the nuanced distinctions that could uncover the true nature of early stars.

Galaxy of the supernova

Webb not only witnessed the explosion. It also assisted in identifying the home galaxy of the supernova, which is quite a challenge when examining such distant times. At those distances, galaxies may be so small and dim that they merge into only a handful of pixels.

“Webb’s findings suggest that this remote galaxy resembles other galaxies from the same era,” stated Emeric Le Floc’h, a co-author and astronomer at CEA Paris-Saclay in France.

Currently, what researchers can understand about the galaxy is restricted since its light merges into a small blur. Nonetheless, the ability of Webb to observe it at all is significant.

The observation provides researchers with a foundation for tackling larger questions, such as the growth rate of galaxies in the early universe and the lifespan of their stars.

Insights from GRB 250314A

The team employed a quick-response observing program to investigate supernova GRB 250314A and is currently organizing additional studies.

The concept involves utilizing gamma-ray bursts as markers: detect the burst, follow the afterglow, and use that illumination to uncover the galaxy that experienced the occurrence.

"That brightness will assist Webb in observing further and provide us with a 'fingerprint' of the galaxy," Levan stated.

Overall, this is where contemporary astronomy excels: responding swiftly, collaborating globally, and capturing transient signals before they disappear.

Webb is designed for intricate, profound infrared observations, and in this instance, it transformed a fleeting burst into a vivid narrative about a star that perished while the universe was still in its infancy.

The complete research was released in the journal Astronomy and Astrophysics Letters