MSU physicist recreates neutron star reaction, reveals how explosive stars forge elements
Contact: Sarah Nicholas
STARKVILLE, Miss.—A Mississippi State physicist has achieved a significant scientific advancement, producing a direct laboratory measurement of a key nuclear reaction believed to occur during explosive bursts on neutron stars. These bursts forge heavier elements—the building blocks of planets and life on Earth.
The findings appear in The Astrophysical Journal, a top-rated peer-reviewed journal in astrophysics. The article is online at www.iopscience.iop.org/article/10.3847/1538-4357/ae3de6/meta.
“The universe began almost entirely with hydrogen and helium,” said principal investigator Jaspreet Randhawa, assistant professor in MSU’s Department of Physics and Astronomy. “Every heavier element—from the oxygen we breathe to the iron in Earth’s core—was forged later in stars and stellar explosions. By identifying how stellar explosions build heavier elements, scientists gain a clearer picture of how the elements that form planets and support life are distributed through the cosmos.
“We wanted to know whether nature had a built-in roadblock that stopped heavier elements from forming during X-ray bursts on neutron star surfaces,” added Randhawa, whose graduate student, Muhammad Asif Zubair, joined the study. “Our measurements show this roadblock is much weaker than expected, meaning the process that builds heavier elements can continue.”
Neutron stars are the dense remnants left behind when massive stars explode, Randhawa said. Though only about the size of a city, they can pack more mass than the sun. In some binary systems, they pull in material from a companion star, creating extreme temperatures and pressures that trigger bursts of X-rays.
Scientists have long suspected that the process of forming heavier elements in these bursts could stall at copper-59, a short-lived isotope that decays in less than two minutes. That brief window has made it difficult for researchers to study the reaction in a laboratory, posing a major challenge for direct measurement, Randhawa said.
In this new study, he and his colleagues on the international team produced a beam of copper-59, accelerated it, and directed it onto a frozen hydrogen target before it decayed. The experiment took place at TRIUMF, Canada’s national laboratory for nuclear and particle physics, one of the few facilities in the world capable of producing beams of copper-59 in sufficient quantities for study. This was the first direct laboratory measurement of this key reaction.
For more about MSU’s College of Arts and Sciences or the Department of Physics and Astronomy, visit www.cas.msstate.edu or www.physics.msstate.edu.
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