An international team of scientists has uncovered new clues about how stars lived and died billions of years ago by studying one of the largest structures in the universe: the Perseus Cluster.
Located deep in the Perseus constellation, the Perseus Cluster contains more than a thousand galaxies surrounded by an enormous cloud of superheated gas.
This gas shines brightly in X-rays and contains chemical traces left behind by countless exploding stars, known as supernovae, over billions of years.
For years, astronomers have studied these chemical patterns to better understand how stars create elements such as silicon, sulfur, argon, calcium, and zinc.
But observations from the Japanese X-ray space telescope Hitomi revealed something unexpected.
The amounts of several elements inside the cluster did not match predictions from standard theories of how massive stars evolve and explode.
This suggested that scientists’ current models of stellar evolution were incomplete.
To solve the mystery, researchers from institutions including The University of Tokyo and the Netherlands Institute for Space Research created a new generation of computer models describing the lives and deaths of massive stars.
The studies were published in The Astrophysical Journal.
The researchers first redesigned models of massive stars that are at least 10 times heavier than the sun. Their updated models were finally able to reproduce the unusual amounts of silicon, sulfur, argon, and calcium seen in the Perseus Cluster.
Next, the team expanded the work by building a huge catalog of star models covering stars between 15 and 60 times the mass of the sun.
The models also included stars with different “metallicities,” a term astronomers use to describe the chemical makeup of stars formed at different times in cosmic history.
Using these simulations, the researchers reconstructed more than 10 billion years of chemical evolution inside galaxy clusters. This helped them understand how generations of exploding stars gradually enriched the universe with heavy elements.
The scientists also investigated a more extreme type of stellar explosion involving powerful jets. These explosions happen when a rapidly rotating star collapses into a black hole or neutron star. As material spins around the collapsed object, it can launch enormous jets of energy through the star.
The team ran advanced multidimensional simulations to study these violent events. They found that jet-driven explosions may produce unusually large amounts of zinc. Because of this, zinc could act like a “fingerprint” showing how often these rare explosions happened in the early universe.
The researchers say their work not only improves understanding of the Perseus Cluster, but could also help explain the chemical history of our own Milky Way.
In the future, the team plans to use data from the new X-ray mission XRISM to continue studying galaxy clusters and the long history of exploding stars across the universe.
Source: KSR.
