Kilonova and host galaxy

The Webb Telescope captured an exceptionally bright gamma-ray burst, GRB 230307A, along with its associated kilonova. Kilonovas are explosions produced by a neutron star merging with either a black hole or another neutron star, and are extremely rare, making these events difficult to observe.

Using its highly sensitive infrared capabilities, Webb not only helped scientists identify the home galaxy of the two neutron stars that created the kilonova, but also detected the rare element tellurium in the aftermath of their collision. This provides direct evidence that such cosmic mergers forge heavy elements found on Earth, deepening our understanding of how the universe builds its chemical complexity.

This image from Webb’s NIRCam (Near-Infrared Camera) highlights GRB 230307A’s kilonova and its former home galaxy, set against a backdrop of distant galaxies and foreground stars. The neutron stars were ejected from their home galaxy and traveled a distance of about 120,000 light years, approximately the diameter of the Milky Way, before finally merging several hundred million years later.

[The former host galaxy is the large spiral galaxy most centrally located in the image, and the gamma-ray burst appears as a small red dot near the top-left corner. See the reference image below.]

Release Date: October 25, 2023