Scientists are closer than ever to understanding how stars forge the elements that make up our planet, our bodies, and virtually everything around us, and they’re getting a clearer picture of where stellar explosions fit into the story. New research published in two different papers looks at how stars forge elements as they explode, and how these supernova explosions spread those elements (and other elements that stars have forged during their lives) throughout the cosmos. Astronomers have been studying the bright supernova deaths of massive stars for centuries, but I still don’t quite understand how these explosions occur. The first article looked at a way to investigate supernovae. It uses a radioactive element produced by these explosions called titanium-44, which persists long after supernovae fade. Researchers have now gathered experimental evidence determining how much titanium-44 is created in a supernova, and have found that these cosmic explosions produce 35% more of this element than expected. With this knowledge in hand, scientists can now develop robust computer models of supernovae and compare these models with astronomical observations. This could bring them much closer to understanding how these explosions progress. You may like “It’s exciting to see how far this field has come,” Christopher Cousins, a postdoctoral researcher in the Nuclear Physics Group at the University of Surrey, said in a statement. “A measurement like this would have been considered out of reach just a couple of decades ago, but it now gives us new insight into one of the biggest unanswered questions in astrophysics.” One illustration shows a “vampire” neutron star feeding on a nearby companion star. (Image credit: Robert Lea (created with Canva)) The second article focused on a particular type of stellar explosion called a Type I supernova. These occur when a dense stellar remnant called a neutron star entrains material from a companion stellar body. The intense gravitational influence of the neutron star – a stellar corpse that is one to two times the mass of the Sun crammed into a body about 20 kilometers (12 miles) wide – means that when this stolen stellar matter hits its surfaces, a thermonuclear explosion is triggered. These explosions forge heavy elements and release incredible amounts of energy, some in the form of X-ray bursts. The authors of this paper, coming from the Rare Isotope Beam Facility (FRIB) in Michigan, studied the nuclear reaction that triggers This revealed the long-debated role of the so-called nickel-copper cycle, the temporary trapping of nuclear material during supernovae. Until now, scientists did not know whether the material was trapped in the nickel-copper cycle during X-ray bursts. This research reveals that this happens, but only in small proportions. It gives scientists a clearer picture of how Type I supernovae proceed. One illustration shows a supernova explosion bombarding Earth. (Image credit: Super-Kamiokande Collaboration) “Despite decades of research, we still do not fully understand the nuclear reactions that drive some of the most spectacular stellar explosions in the universe,” said Gavin Lotay of the University of Surrey. “These two studies give us a much clearer picture of how these explosions occur, allowing us to compare our models more closely with astronomical observations and bringing us closer to understanding how chemical elements are created and spread throughout the universe,” he added. Two articles were published in the July issue of the journal Physical Review Letters.
