Astronomers have discovered an unprecedented way to destroy a star

Astronomers study a powerful gamma-ray burst (GRB) using the Gemini South telescope, which is operated by NSF NOIRLabHe may have discovered an unprecedented way to destroy a star. Unlike most GRBs, which are caused by exploding massive stars or possible neutron star mergers, astronomers have concluded that GRBs came instead from the collision of stars or stellar remnants in the crowded environment surrounding a massive star. Black hole In the heart of an ancient galaxy.

The nature of star death

Stars in the universe usually end their lives in predictable ways determined by their mass. Relatively low-mass stars like our Sun shed their outer layers in old age and eventually fade into white dwarf stars. More massive stars burn brighter and die sooner in catastrophic supernova explosions, creating ultra-dense objects like neutron stars and black holes. If two of these stellar remnants form a binary system, they could also eventually collide. However, new research points to a fourth option that has been long hypothesized, but never seen before.

This artist’s impression shows how astronomers studying a powerful gamma-ray burst (GRB) using the Gemini South telescope, operated by NSF’s NOIRLab, may have discovered an unprecedented way to destroy a star. Unlike most GRBs, which are caused by exploding massive stars or possibly merging neutron stars, astronomers have concluded that these GRBs instead came from collisions of stars or stellar remnants in the crowded environment surrounding a supermassive black hole at the galactic core. old galaxy

Discover new discoveries

In searching for the origins of the Long Duration GRB, astronomers used the Gemini South Telescope in Chile, part of the Gemini International Observatory operated by the National Science Foundation’s NOIRLab, as well as the Northern Optical Telescope and Astronomy Observatory. NASA/European Space Agency Hubble Space TelescopeThey detected evidence of stars colliding, or stellar remnants, in a demolition derby-like fashion in the densely packed, chaotic region near the supermassive black hole of an ancient galaxy.

“These new findings show that stars can face their demise in some of the densest regions of the universe where they can be pushed into collision,” said Andrew Levan, an astronomer at Radboud University in the Netherlands and lead author of the paper that appeared in the journal Radboud. Nature Astronomy Journal. “This is exciting for understanding how stars die and answering other questions, such as what unexpected sources might create the gravitational waves that we can detect on Earth.”

Observational evidence and results

Ancient galaxies are long past the beginning of star formation and will have few, if any, giant stars remaining, which are the main source of long GRBs. However, their cores are teeming with stars and a collection of superdense remnants, such as white dwarfs, neutron stars, and black holes. Astronomers have long suspected that in a hive turbulent from activity surrounding a supermassive black hole, it would be only a matter of time until two stellar objects collided to produce GRBs. However, the evidence for this type of fusion remains elusive.

Astronomers studying a powerful gamma-ray burst (GRB) with the Gemini International Observatory, managed by NSF’s NOIRLab, may have noticed an unprecedented way to destroy a star. Unlike most GRBs, which are caused by exploding massive stars or possibly merging neutron stars, astronomers have concluded that these GRBs instead came from collisions of stars or stellar remnants in the crowded environment surrounding a supermassive black hole at the galactic core. old galaxy Source: Gemini Observatory International/NOIRLab/NSF/AURA/M. Garlick / M. my time

The first hints of such an event were seen on October 19, 2019 when NASA’s Neil Gehrels Swift Observatory detected a bright flash of gamma rays that lasted just over a minute. Any GRB burst lasting more than 2 seconds is considered “long”. Such explosions usually come from the supernova death of stars at least 10 times the mass of our Sun, but not always.

The researchers then used Gemini South to make long-term observations of the fading afterglow of the GRB explosions to learn more about its origins. The observations allowed the astronomers to locate the GRB explosions in a region less than 100 light-years from the nucleus of an ancient galaxy, placing them near the galaxy’s supermassive black hole. The researchers also found no evidence of a similar supernova, which would have left its mark on the light studied by Gemini South.

Insight into the origins of the GRB

“Our subsequent observations told us that rather than being a massive collapsing star, the explosion was most likely caused by the merger of two merging objects,” Levan said. “By locating it at the center of an ancient, previously identified galaxy, we have obtained the first tantalizing evidence of a new trajectory for stars to meet their demise.”

From a dizzying height, the full scope and dimension of the Gemini South Telescope, half of the Gemini International Observatory, managed by NSF’s NOIRLab, can be achieved. Gemini South is located on Mount Cerro Bachon at an altitude of 2,715 meters (8,900 ft) above sea level, and benefits from the stable conditions of the microclimate. The dry air that makes it easier for a telescope to “see” is almost palpable over the sprawling Chilean Andes in the background. This image also captures the telescope’s 8-meter mirror peering through the dome structure, an unusual occurrence for daylight hours, and the solar panels (lower right), which power the telescope during nighttime observations of the southern sky. Source: Gemini Observatory International/NOIRLab/NSF/AURA/T. Matsopoulos

In normal galactic environments, the production of long GRBs from the remnants of colliding stars such as neutron stars and black holes is thought to be rare. However, the cores of ancient galaxies are not normal at all, and there may be a million or more stars crammed into a region only a few light-years across. Such an intense population density might be large enough that stellar collisions would occasionally occur, especially under the gigantic gravity of a supermassive black hole, which would perturb the motions of the stars and send them off in random directions. Eventually, these stray stars will intersect and merge, resulting in a massive explosion that can be seen from vast cosmic distances.

It is possible that such events occur routinely in similar crowded regions throughout the universe but have been unnoticed until this point. One possible reason for its opacity is that the galactic centers are filled with dust and gas, which could obscure both the GRB’s initial flash and the resulting afterglow. This type of GRB has been identified as GRP 191019aThis may be a rare exception, allowing astronomers to detect the explosion and study its aftereffects.

Future research and its implications

Researchers want to find out more about these events. They hope to match the discovery of GRBs with the corresponding detection of gravitational waves, which would reveal more about their true nature and confirm their origins, even in the most mysterious of environments. The Vera C. Rubin Observatory, when it is ready for use in 2025, will be invaluable in this type of research.

“Studying gamma ray bursts like this one is a great example of how the field has already advanced with so many facilities working together, from detection of GRBs, to detections of auroras and distances with telescopes like Gemini, right down to detailed dissections of events,” Levan said. “With Observations Across the Electromagnetic Spectrum”.

“These observations add to Gemini’s rich legacy and advance our understanding of star evolution,” says Martin Steele, NSF program manager at the Gemini International Observatory. “The time-sensitive observations are a testament to Gemini’s intelligent processes and sensitivity to dynamic, distant events across the universe.”

Reference: “Long-period Gamma-Ray Burst of Dynamical Origin from an Ancient Galactic Core” by Andrew J. Levan, Daniele B. Malesani, Benjamin P. Gompertz, Anya E. Nugent, Matt Nicholl, Samantha R. Oates, Daniel A. Burleigh, Gillian Rastingad, Brian D. Metzger, Steve Schulz, Elizabeth R. Stanway, Anne Enckenhage, Taiba Zafar, J. Feliciano Agui Fernandez, Ashley A. Krems, Kornbob Birumbakdi, Antonio de Ugarte Postigo, Wen Fei Fung, Andrew S. Fruchter, Giacomo Fragioni, Johann Bo Venpo, Nicola Gaspari, Casper E. Heintz, Jens Hegworth, Pal Jacobson, Peter J. Junker, Gavin B. Lamb, Elijah Mandel, Sohaib Mandhai, Maria E. Ravasio, Jesper Sullerman, and Niall R. Tanvir, June 22, 2023, Available Here. Nature Astronomy.
doi: 10.1038/s41550-023-01998-8

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Reference: “Long-period Gamma-Ray Burst of Dynamical Origin from an Ancient Galactic Core” by Andrew J. Levan, Daniele B. Malesani, Benjamin P. Gompertz, Anya E. Nugent, Matt Nicholl, Samantha R. Oates, Daniel A. Burleigh, Gillian Rastingad, Brian D. Metzger, Steve Schulz, Elizabeth R. Stanway, Anne Enckenhage, Taiba Zafar, J. Feliciano Agui Fernandez, Ashley A. Krems, Kornbob Birumbakdi, Antonio de Ugarte Postigo, Wen Fei Fung, Andrew S. Fruchter, Giacomo Fragioni, Johann Bo Venpo, Nicola Gaspari, Casper E. Heintz, Jens Hegworth, Pal Jacobson, Peter J. Junker, Gavin B. Lamb, Elijah Mandel, Sohaib Mandhai, Maria E. Ravasio, Jesper Sullerman, and Niall R. Tanvir, June 22, 2023, Available Here. Nature Astronomy.
doi: 10.1038/s41550-023-01998-8