What is a superkilonova?

IN NEWS: Superkilonova

A recent international study reported observations of a possible superkilonova event about 1.3 billion light-years away.
The study involved researchers from IIT Bombay and the Indian Institute of Astrophysics, Bengaluru.
The findings were reported in The Hindu following publication of the study on 15 December 2025.

A superkilonova is a rare and hypothetical cosmic explosion.
It is related to, but more energetic than, a kilonova.
A kilonova occurs when two neutron stars merge, ejecting matter rich in heavy radioactive elements such as gold, platinum and neodymium.
The radioactive decay of these elements produces emissions in the optical and infrared spectrum.

A neutron star is the collapsed core of a massive star after a supernova.
It is extremely dense, composed primarily of neutrons.
Neutron star mergers are among the strongest sources of gravitational waves.

Two neutron stars orbit each other and eventually collide.
The merger ejects neutron-rich material into space.
This material undergoes rapid neutron capture (r-process), forming heavy elements.
The decay of these elements produces a short-lived but intense glow called a kilonova.

A superkilonova has an additional energy source beyond radioactive decay.
One proposed mechanism:
- Some ejected matter falls back toward the merged object.
- This fallback matter heats up and transfers energy to surrounding ejecta.
- The result is a brighter, bluer and longer-lasting emission than a normal kilonova.
Another proposed scenario:
- A supernova explosion first forms two neutron stars.
- These neutron stars later merge, producing a kilonova.
- The combined energy output leads to a superkilonova-like signature.

The observed event initially resembled a kilonova for about three days.
Later, its light characteristics shifted and began to resemble a supernova.
The brightness and spectral “fingerprint” matched predictions for a superkilonova.
Astronomers emphasised that more such observations are needed to confirm the phenomenon conclusively.

Helps improve understanding of:
- Formation of heavy elements in the universe
- Stellar evolution and death
- Extreme astrophysical explosions
May bridge the observational gap between supernovae and kilonovae.
Enhances multi-messenger astronomy involving light and gravitational waves.

Collection of more observational data on similar cosmic events.
Improved sky surveys and rapid follow-up observations.
Integration of electromagnetic observations with gravitational-wave detectors.
Refinement of theoretical models explaining neutron star mergers and stellar explosions.

Updated – 21 December 2025 ; 02:32 PM IST | News Source: The Hindu