SVOM Captures One of the Most Distant Star Explosions — A 13‑Billion‑Year Cosmic Flash

An immensely powerful gamma‑ray flash spotted on March 14 was produced by a massive star that exploded when the universe was only about five percent of its current age, astronomers said Tuesday. The event, designated GRB250314A, was detected by SVOM, a French–Chinese space telescope launched last year to hunt gamma‑ray bursts.

Rare Window Into the Early Universe

According to two studies in Astronomy & Astrophysics, the burst originated from a star roughly 100 times the mass of the Sun that detonated about 700 million years after the Big Bang. "This is extremely rare — it's the fifth most distant gamma‑ray burst ever detected," said Bertrand Cordier, the French Atomic Energy Commission's (CEA) scientific lead for SVOM and co‑author of both papers. He noted that the photons reaching our instruments traveled about 13 billion years to arrive on Earth.

"The photons that reached our instruments travelled for 13 billion years," — Bertrand Cordier, CEA.

Why Gamma‑Ray Bursts Matter

Gamma‑ray bursts (GRBs) are the most energetic explosions known, thought to result from catastrophic events such as the collapse of very massive stars or the merger of compact objects like neutron stars. In seconds, a GRB can emit as much energy as our Sun will release in its entire ~10‑billion‑year lifetime. Their jets push matter at speeds close to light and illuminate the material they pass through, turning them into powerful probes of the early cosmos.

Detection, Follow‑Up and What Comes Next

SVOM's initial alert mobilized the astronomy community, but follow‑up observations require rapid coordination. In this case, the Very Large Telescope in Chile began observations about 17 hours after the initial detection, by which time the burst had faded. Cordier said better response times would yield richer data, and SVOM aims to catch one or two comparable events per year if the network of follow‑up telescopes can react more quickly.

Researchers say GRB250314A likely came from one of the universe's first generations of stars — objects that forged the first heavy elements such as carbon, oxygen and iron and helped shape later cosmic evolution. The unusually precise light measurements from this distant burst provide a rare glimpse into conditions during the universe's formative epochs.

Key facts: GRB250314A was detected on March 14 by SVOM; the source star was ~100× the Sun in mass; the explosion occurred ~700 million years after the Big Bang; detected photons traveled ~13 billion years to reach Earth; it ranks as the fifth most distant GRB on record.