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Picture Courtesy: The Hindu

Context:

Q: What are the proposed mechanisms behind a superkilonova?

Two main mechanisms are proposed: a fallback-powered process, where ejected matter falls back and heats the merger remnant, and a supernova-triggered process, where a supernova is followed by a rapid neutron-star merger.

Q: Why are superkilonovae important for understanding heavy elements?

Superkilonovae, like kilonovae, involve r-process nucleosynthesis, which is responsible for forming heavy elements such as gold and platinum, thereby improving understanding of the universe’s chemical evolution.

Q: How are superkilonovae detected?

Superkilonovae are detected through optical and infrared telescopes by analysing their light curves and spectra, and future confirmation may involve gravitational-wave observations.

In a study of an international research team -- including from IIT-Bombay and the Indian Institute of Astrophysics, Bengaluru -- reported a possible discovery of Superkilonova.

Background of Kilonova:

When two neutron stars collide, enormous amounts of matter are ejected into space.
This ejecta is rich in heavy radioactive elements such as gold, platinum, and neodymium, formed via rapid neutron capture (r-process).
As these elements decay, they emit light primarily in the optical and infrared
This transient glow is called a kilonova, typically lasting days to weeks.

What is a Superkilonova?

A superkilonova is a hypothetical and extremely rare cosmic explosion that appears brighter, bluer, and longer-lasting than a normal kilonova, due to an additional energy source beyond the standard neutron-star merger.

It represents a new class of stellar explosion, still under scientific investigation.

Recent Scientific evidences:

An international research team, including scientists from the Indian Institute of Astrophysics and the Indian Institute of Technology Bombay, reported observations of a candidate superkilonova.
The event was detected at a distance of approximately 3 billion light-years from Earth.
Observational data showed that the object initially resembled a kilonova for about three days, before evolving to display supernova-like characteristics, supporting the idea of a hybrid explosion.

What makes a Superkilonova different?

A superkilonova differs from a standard kilonova because it involves additional energy input, which makes the explosion more luminous, bluer, and longer-lasting than what is produced by a simple neutron-star merger.

Fallback-Powered Superkilonova

After two neutron stars merge, a fraction of the ejected matter can fall back onto the newly formed compact remnant.
This fallback material becomes extremely hot, releasing extra thermal energy.
The additional heat re-energises the surrounding ejecta, causing the explosion to appear brighter, shift towards bluer wavelengths, and remain visible for a longer duration than a typical kilonova.

Supernova-Triggered Superkilonova (New Hypothesis)

In this proposed mechanism, a massive star first explodes as a supernova, leading to the formation of two neutron stars.
These neutron stars then merge shortly after, producing a conventional kilonova.
The combined light emission from the initial supernova and the subsequent neutron-star merger produces an enhanced, superkilonova-like observational signature.

Significance of this discovery:

The proposed superkilonova challenges existing models of stellar death and explosive astrophysical phenomena.
It offers a possible explanation for unusually bright transient events that were previously difficult to classify.
It enhances scientific understanding of heavy-element formation, neutron star evolution, and extreme energy-release processes in the universe.

Conclusion:

A superkilonova represents a potentially new and powerful class of cosmic explosion that bridges supernovae and kilonovae, offering fresh insights into stellar evolution, heavy-element synthesis, and extreme astrophysical energy processes, while highlighting the need for further observations to firmly establish its nature.

Source: The Hindu

Attempt Daily Quiz

Practice Questions

1. With reference to a superkilonova, consider the following statements:

1. It is associated with the merger of neutron stars and the synthesis of heavy elements through r-process nucleosynthesis.

2. It is brighter and longer-lasting than a standard kilonova due to the presence of an additional energy source.

3. It has been conclusively established as a distinct and well-confirmed class of cosmic explosion.

Which of the statements given above are correct?
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3

Answer: (a)

With reference to a superkilonova, consider the following statements

Statement 1 correct: It is associated with the merger of neutron stars and the synthesis of heavy elements through r-process nucleosynthesis.
Like a normal kilonova, a superkilonova involves neutron-star mergers that eject neutron-rich matter, enabling r-process nucleosynthesis, which forms heavy elements such as gold, platinum, and neodymium.

Statement 2 correct: It is brighter and longer-lasting than a standard kilonova due to the presence of an additional energy source.

The defining feature of a superkilonova is extra energy input (fallback heating or a preceding supernova), making it more luminous, bluer, and longer-lived than a typical kilonova.

Statement 3 incorrect: It has been conclusively established as a distinct and well-confirmed class of cosmic explosion.
Superkilonovae are still hypothetical; current observations are candidate events, and more data are required for confirmation.

Frequently Asked Questions (FAQs)

Two main mechanisms are proposed: a fallback-powered process, where ejected matter falls back and heats the merger remnant, and a supernova-triggered process, where a supernova is followed by a rapid neutron-star merger.

Superkilonovae, like kilonovae, involve r-process nucleosynthesis, which is responsible for forming heavy elements such as gold and platinum, thereby improving understanding of the universe’s chemical evolution.

Superkilonovae are detected through optical and infrared telescopes by analysing their light curves and spectra, and future confirmation may involve gravitational-wave observations.