Overview
- A study in The Astrophysical Journal Letters identifies AT2025ulz as a possible first example of a supernova followed quickly by a kilonova.
- LIGO and Virgo issued a low-confidence alert on August 18 indicating a merger that involved at least one unusually low-mass object.
- Hours after the alert, the Zwicky Transient Facility observed a rapidly fading red source consistent with a kilonova that later brightened and displayed hydrogen and helium lines typical of a Type IIb supernova about 1.3 billion light-years away.
- Caltech-led researchers propose that a rapidly spinning star exploded and produced two sub-solar-mass neutron stars that merged shortly afterward within the supernova debris.
- The authors stress the gravitational-wave and optical association is unproven and call for additional multimessenger detections to test the superkilonova hypothesis.