While searching for the origin of a powerful gamma-ray burst (GRB), an international team of astrophysicists may have stumbled upon a new way for stars to annihilate.
While 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 crowded environment surrounding a supermassive black hole at the center of an ancient galaxy. The star-collapse derby points to a long-hypothesized but never-before-seen way of collapsing a star to produce a GRB.
„It’s exciting for understanding how stars die and for answering other questions, such as unexpected sources of gravitational waves that we can detect on Earth.”
Led by Radbot University in the Netherlands, the research team included astronomers Northwestern University. Study, published Natural AstronomySupported in part by several grants from the US National Science Foundation listed at the end of this article.
„For every hundred events that fit the traditional classification scheme of gamma-ray bursts, at least one oddball will throw us into a loop,” said Wen-Fi Fang, a Northwestern astrophysicist and study co-author. „However, it is these oddballs that tell us the most about the universe’s amazing diversity of potential explosions.”
Giacomo Fragione, a Northwestern astrophysicist and study co-author, said, „This remarkable discovery gives us an exciting glimpse into the complex dynamics at work in these cosmic environments, establishing them as factories of phenomena that would otherwise be considered impossible.”
Most stars die in proportion to their mass in one of three predictable ways. As relatively low-mass stars like our Sun age, they shed their outer layers and eventually become white dwarf stars. On the other hand, very massive stars burn brightly and explode rapidly in cataclysmic supernova explosions, creating ultradense objects such as neutron stars and black holes. A third scenario occurs when two such stellar remnants form a binary system and eventually collide.
But new research finds there may be a fourth option.
„Our results show that stars can meet their doom in some of the densest regions of the Universe, where they can be driven to collide,” said lead author Andrew Levin, an astronomer at Radboud University. „It’s exciting for understanding how stars die and for answering other questions, such as unexpected sources of gravitational waves that we can detect on Earth.”
On October 19, 2019, NASA’s Neil Gehrles Swift Observatory detected a bright burst of gamma rays that lasted more than a minute. Any GRP that lasts longer than two seconds is considered „long.” Such explosions typically come from the collapse of stars at least 10 times the mass of our Sun.
The researchers used the Gemini South Telescope in Chile International Gemini Observatory Operated by NSFs NOIRLab – To carry out long-term observations of the GRB’s dimming regression.
By working to find more of these events, researchers hope to match GRB detection with related gravitational-wave detection, which will reveal more about their true nature and confirm their origin – even in very dark environments. The Vera C. Rubin ObservatoryWhen it comes online in 2025, such research will be invaluable, scientists say.
NSF supported the research through the following grants: AST-1814782AST-1909358AST-2047919and AST-2108624.
The research is also based on observations obtained at the International Gemini Observatory, a project of NOIRLab, which is managed by the Association of Universities for Astronomical Research under a cooperative agreement with NSF on behalf of the Gemini Observing Partnership. In partnership with NSF, the National Research Council (Canada), Agenzia Nacional de Investigación y Desarrollo (Chile), Ministerio de Ciencia, Tecnologia e Innovação (Argentina), Ministerio da Ciencia, Coriasica, Innova Coracia Institute of Astronomy and Space Sciences (Republic of Korea).
Data were processed using the Gemini IRAF package and Dragons, Gemini Observatory North and South Astronomical Data Reduction, NSF grant AST.1238877.
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