Indian Scientists Study Supernova SN 2023zcu to Strengthen the Cosmic Distance Scale

Indian astronomers have contributed to an important study of SN 2023zcu, a newly discovered supernova located at the edge of the spiral galaxy NGC 2139, around 90.7 million light-years from Earth. The study helps scientists understand how such stellar explosions evolve and how they can be used to measure distances in the nearby universe.

A supernova is one of the most powerful explosions in space. It occurs when a massive star reaches the end of its life, exhausts its nuclear fuel and collapses under gravity. The blast releases enormous energy and spreads heavy elements into space. These elements later become part of new stars, planets and even the basic material needed for life.

SN 2023zcu belongs to the Type IIP class of core-collapse supernovae. Such explosions usually come from red supergiant stars with masses about 8 to 17 times greater than the Sun. Their brightness stays nearly steady for a few months after the explosion, creating a “plateau” in the light curve. This makes Type IIP supernovae especially useful for scientific study because their behaviour can be measured in a more predictable way.

The supernova was discovered on 8 December 2023, within a day of the explosion. This early discovery allowed scientists to observe it through different phases, including the early shock-cooling stage, the plateau phase and the later nebular phase. Ground-based and space-based telescopes were used for detailed photometric and spectroscopic observations.

The research was carried out by Monalisa Dubey, Dr. Kuntal Misra and Naveen Dukiya from the Aryabhatta Research Institute of Observational Sciences, an autonomous institute under the Department of Science and Technology, along with international collaborators. The study has been published in The Astrophysical Journal.

One of the key achievements of the study is the distance estimation of SN 2023zcu using the Expanding Photospheric Method. This method compares the actual size of the expanding supernova surface with its observed brightness. The study estimated the supernova’s distance at about 27 megaparsecs, supporting its use in refining the cosmic distance scale.

The observations also revealed that the star had lost only a small amount of mass before the explosion. During the plateau phase, scientists detected strong hydrogen features and lines of elements such as iron, sodium and calcium. In the later nebular phase, emission lines from oxygen, iron, calcium and magnesium became visible as the expanding material grew thinner.

By modelling the total energy output of the supernova, researchers estimated that the original star had a mass of around 12 times that of the Sun and an explosion energy of about 2 × 10⁵¹ ergs. These values are typical of red supergiant explosions and help scientists understand the physical nature of the star before it died.

This study shows how careful monitoring of a single stellar explosion can improve knowledge of the universe. Supernovae are cosmic laboratories, chemical factories and distance markers at the same time. By studying SN 2023zcu in detail, Indian scientists have added valuable data to the global effort to understand stellar death, galaxy distances and the structure of the local universe.

Publication link: https://ui.adsabs.harvard.edu/abs/2026ApJ…999…93D/abstract

Source: PIB