Astronomers have potentially witnessed the first-ever “superkilonova”—a cosmic double explosion that challenges everything we know about stellar death and threatens to rewrite fundamental astrophysics textbooks.
Story Highlights
- Scientists detected AT2025ulz on August 18, 2025, showing unprecedented double explosion pattern
- Event produced sub-solar mass neutron stars, defying standard stellar formation models
- Discovery combines supernova and kilonova in single stellar death, creating new classification
- Gravitational wave detection by LIGO-Virgo confirmed neutron star merger 1.8 billion light-years away
Groundbreaking Discovery Challenges Scientific Consensus
On August 18, 2025, the LIGO and Virgo gravitational wave detectors captured signals from a neutron star merger approximately 1.8 billion light-years away. Within hours, the Zwicky Transient Facility at Palomar Observatory identified optical counterpart AT2025ulz, displaying behavior that stunned the scientific community. The transient initially appeared as a typical kilonova with reddish, fast-fading light, then unexpectedly rebrightened and showed hydrogen signatures characteristic of supernovae.
Revolutionary Formation Mechanism Unveiled
Lead astronomer Mansi Kasliwal from Caltech and theorist Brian Metzger from Columbia University propose a radical formation scenario. A massive, rapidly spinning star underwent core collapse, potentially fragmenting into two low-mass neutron stars that quickly merged within the supernova ejecta. This process created what researchers term a “kilonova inside a supernova”—an entirely new class of cosmic explosion. The gravitational wave analysis revealed at least one neutron star with mass below one solar mass, contradicting standard neutron star formation models.
Scientific Caution Amid Revolutionary Claims
Despite the excitement, researchers maintain careful scientific skepticism. Kasliwal emphasizes the team is “very careful to say this is a candidate, not slam dunk evidence.” The superkilonova classification remains hypothetical, requiring additional similar events for confirmation. Current uncertainties include the exact progenitor mass, rotation rate, and formation mechanism—whether through core fission or disk-formed companion neutron stars. Multiple observatories including Keck contributed spectral and photometric data to support the analysis.
This discovery potentially revolutionizes our understanding of heavy element production in the universe. Superkilonovae could serve as particularly efficient factories for creating gold, platinum, and other precious metals through combined supernova and kilonova processes. The finding also enhances the importance of multi-messenger astronomy, combining gravitational wave and electromagnetic observations to unlock cosmic mysteries previously hidden from scientific inquiry.
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A double cosmic explosion could be the first known ‘superkilonova’
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