The Superkilonova Symphony: Merging Stars Inside Exploding Ones (AT2025ulz and S250818k)
Published: January 12, 2026
Duration: 17:24
In this episode, we dive into a groundbreaking discovery that may have revealed a brand-new category of cosmic explosion: the Superkilonova. On August 18, 2025, gravitational-wave detectors picked up a signal, S250818k, indicating a merger between two neutron stars—but with a twist. The estimated "chirp mass" was surprisingly low, suggesting that at least one of the objects was below the mass of our Sun, a finding that challenges standard models of stellar evolution.
The Optical Mystery:
The Zwicky Transient Facility (ZTF) quickly identified a matching optical transient, AT2025ulz, in the same re...