Time and again, scientists have said that stars are the most basic building blocks of galaxies. From Red giant star, T Tauri star, Sirius to Neutron star, there are innumerable types of stars that have kept the stargazers captivated to the night sky. But now it seems the night sky enthusiasts have something new to explore about stars as researchers have documented a giant “hiccupping” star in the last stages of its life before exploding, for the first time.
The rare cosmic event only occurs with exceptionally large stars between 60 to 150 times the mass of the Sun and Pulsational Pair Instability (PPI) or “hiccupping” happens when a star develops a very hot core, which contracts and expands quickly in the final phase of its life. Though this has been predicted in theory but was never seen before.
‘We Saw Light Coming from the Same Region’
Scientists explained that every time a star pulsates, it ejects shell material, which strips down the core star. These shells can then collide with each other, creating intense bursts of light.
Recently, the international team of researchers, including astrophysicists from Queen’s University Belfast, were able to record the event by coordinating observations from telescopes around the world. The results of the study were published in the Astrophysical Journal.
Lead author Dr. Charlotte Angus, from the Astrophysical Research Centre (ARC) at Queen’s University, said that as the shell collisions are much fainter than the final supernova, which is a massive explosion when a star dies, it was not possible for researchers to confirm the theory earlier.
Angus said, “In December 2020, we identified a new bright supernova, now named ‘SN2020acct’, in a nearby spiral galaxy called NGC 2981,” adding “The light from SN2020acct disappeared pretty quickly. But then in February 2021, we saw light coming from the same region of the galaxy again.”
“This is very unusual as supernovae normally don’t reappear,” she added.
First Time Observation
According to the study, the researchers tracked the supernova using telescopes in Hawaii, Chile, South Africa and the US. They discovered that when it appeared for a second time, it was expanding much faster.
This phenomenon suggested that the core of the star had exploded, eventually marking the end of its life. Following this, the researchers used modelling to confirm that the first flare was an example of PPI.
According to the scientists, the star was around 150 times the mass of the Sun and it experienced a series of extreme pulses in the final 50 days before it exploded. Angus said, “This is the first time that we have ever obtained observations of a PPI candidate during the shell collisions, allowing us to confirm for the first time that this is really happening.”
Angus added, “That the data matches the modelling predictions is incredibly exciting.”
