While searching for the origins of a powerful stellar gamma-ray burst (GRB), an international team of astrophysicists may have stumbled upon a new way stars might be destroyed.
Astronomers studying a powerful gamma-ray burst (GRB) with the International Gemini Observatory, operated by NSF’s NOIRLab, may have observed a never-before-seen way to destroy a star. Unlike most GRBs, which are caused by exploding massive stars or the chance mergers of neutron stars, astronomers have concluded that this GRB came instead from the collision of stars or stellar remnants in the jam-packed environment surrounding a supermassive black hole at the core of an ancient galaxy. Image credit: International Gemini Observatory/NOIRLab/NSF/AURA/M. Garlick/M. Zamani
Although most GRBs originate from exploding massive stars or neutron-star mergers, the researchers concluded that GRB 191019A instead came from the collision of stars or stellar remnants in the jam-packed environment surrounding a supermassive black hole at the core of an ancient galaxy.
The stellar demolition derby points to a long-hypothesized but never-before-seen way to demolish a star and generate a GRB.
“This is exciting for understanding how stars die and for answering other questions, such as what unexpected sources might create gravitational waves that we could detect on Earth.”
Led by Radboud University in the Netherlands, the research team included astronomers from Northwestern University. The study, published in Nature Astronomy, was supported in part by several grants from the U.S. National Science Foundation, listed at the conclusion of this article.
“For every hundred events that fit into the traditional classification scheme of gamma-ray bursts, there is at least one oddball that throws us for a loop,” said Northwestern astrophysicist and study co-author Wen-fai Fong.
“However, it is these oddballs that tell us the most about the spectacular diversity of explosions the universe is capable of.”
Added Northwestern astrophysicist and study co-author Giacomo Fragione, “This remarkable discovery grants us a tantalizing glimpse into the intricate dynamics at work in these cosmic environments, establishing them as factories of events that would otherwise be deemed impossible.”
Most stars die, according to their mass, in one of three predictable ways. When relatively low-mass stars like our sun reach old age, they shed their outer layers, eventually fading to become white dwarf stars.
More massive stars, on the other hand, burn brighter and explode faster in cataclysmic supernovae explosions, creating ultra-dense objects like neutron stars and black holes. The third scenario occurs when two such stellar remnants form a binary system and eventually collide.
But the new study finds there might be a fourth option.
“Our results show that stars can meet their demise in some of the densest regions of the universe, where they can be driven to collide,” said lead author Andrew Levan, an astronomer with Radboud University.
“This is exciting for understanding how stars die and for answering other questions, such as what unexpected sources might create gravitational waves that we could detect on Earth.”
On October 19, 2019, NASA’s Neil Gehrels Swift Observatory detected a bright stellar flash of gamma rays that lasted a little more than one minute. Any GRB lasting longer than two seconds is considered “long.” Such bursts typically come from the collapse of stars at least 10 times the mass of our sun.
Source: NSF
