Newly Observed Mechanism for Stellar Demise Unearthed by Astronomers

Utilizing the Gemini South telescope, researchers have posited a previously unobserved mechanism by which stars may meet their end: through collisions proximate to a supermassive black hole within an ancient galaxy. This finding furnishes a renewed understanding of the spatial conditions around such black holes and the as-yet-unobserved collisions taking place there.

Understanding Varieties of Stellar Termination

The lifetime of stars typically concludes in predictable patterns governed by their mass. Less massive stars like our Sun gradually shed their outer layers in their later years, eventually evolving into white dwarf stars. Heavier stars expire more rapidly through spectacular supernova eruptions, leaving behind incredibly dense entities like neutron stars and black holes. Some of these stellar remnants may also form binary systems and eventually crash into each other. Recent research, however, suggests an unobserved, fourth modality for the end of stellar life.

Unearthing Unprecedented Findings

While investigating the origins of a prolonged gamma-ray burst (GRB), astronomers used multiple telescopes—among them, the Gemini South telescope in Chile, operated by NSF’s NOIRLab, the Nordic Optical Telescope, and the NASA/ESA Hubble Space Telescope. They found signs of a catastrophic collision involving stars or stellar remnants within the disorderly and highly populated area near a supermassive black hole at the heart of an archaic galaxy.

“The new data illustrate that stars can be annihilated in some of the Universe’s most densely populated regions where they are influenced to collide,” said Andrew Levan, a Radboud University astronomer and lead author of a paper published in Nature Astronomy.

Evidentiary Observations

Galaxies well past their zenith in star formation would typically lack giant stars, which are the main producers of long GRBs. Nevertheless, these ancient galaxies have a plethora of stars and ultra-dense stellar remnants like white dwarf stars, neutron stars, and black holes in their cores. While it has been suspected that such cluttered environments would eventually lead to collisions that generate a GRB, definitive proof had been lacking.

Preliminary evidence of such a collision was initially recorded on October 19, 2019, by NASA’s Neil Gehrels Swift Observatory, which detected a brief but bright gamma-ray emission. Subsequent observations revealed that the GRB was near a supermassive black hole in an ancient galaxy and lacked any corresponding supernova signature.

Insights into the Origins of GRBs

“Instead of the collapse of a massive star, the most plausible explanation for this burst is the coalescence of two compact objects,” Levan noted. “The burst’s precise location in an already-identified ancient galaxy provided the inaugural compelling evidence for an alternative route for stellar annihilation.”

Galactic Centers: A Hotbed for Stellar Collisions

Ordinarily, collisions between stellar remnants like neutron stars and black holes leading to long GRBs are considered extremely rare. However, the core regions of ancient galaxies are exceptionally crowded, possibly containing millions of stars within a few light-years. Such density, magnified by the enormous gravitational forces of a supermassive black hole, increases the chances of erratic stellar movements leading to collisions and resultant colossal explosions that can be detected even from immense cosmic distances.

Future Prospects

Researchers aim to find more such events and ideally link a GRB observation to a coinciding detection of gravitational waves, thereby revealing more about their nature and confirming their origins. The forthcoming Vera C. Rubin Observatory, scheduled to be operational by 2025, will play a crucial role in this research area.

“Instrumental in advancing our knowledge of stellar evolution, these time-sensitive observations exhibit the nimbleness and sensitivity of Gemini to distant, dynamic cosmic events,” said Martin Still, NSF’s program director for the International Gemini Observatory.

References

The original research paper titled “A long-duration gamma-ray burst of dynamical origin from the nucleus of an ancient galaxy,” authored by Andrew J. Levan and a host of researchers, was published on 22 June 2023 in the journal Nature Astronomy.

For additional context regarding this groundbreaking discovery:

• A Novel Mechanism for Stellar Annihilation
• A Historic Gamma-Ray Burst in the Core of an Age-Old Galaxy

Frequently Asked Questions (FAQs) about Star Destruction Near Supermassive Black Holes

More about Star Destruction Near Supermassive Black Holes

• Gemini Observatory
• NOIRLab
• Nature Astronomy Journal
• Nordic Optical Telescope
• NASA/ESA Hubble Space Telescope
• Vera C. Rubin Observatory
• Radboud University
• Gravitational Waves Overview
• Stellar Evolution
• Gamma-Ray Bursts