2023-06-25 04:00:00
Astronomers studying a powerful gamma-ray burst (GRB) with the Gemini South telescope, operated by the NOIRLab of the National Science Foundation (NSF) in the United States, may have detected a never-before-seen way to destroy a star, they publish in the magazine ‘Nature Astronomy’.
Unlike most GRBs, caused by the explosion of massive stars or the random merger of neutron stars, astronomers have concluded that this GRB was produced by the collision of stars or stellar debris in the crowded environment. surrounding a supermassive black hole at the core of an ancient galaxy.
Most of the stars in the Universe die in a predictable way, depending on their mass. Relatively low-mass stars, like our Sun, shed their outer layers as they age, eventually fading to white dwarfs.
The most massive stars burn hottest and die sooner in cataclysmic supernova explosions, creating ultradense objects like neutron stars and black holes. If two of these stellar remnants form a binary system, they too can end up colliding. However, new research points to a fourth option, long hypothesized but never seen before.
In searching for the origins of a long-duration gamma-ray burst (GRB), astronomers using the Gemini South telescope in Chile, part of the Gemini International Observatory operated by NSF’s NOIRLab, and other telescopes, have uncovered evidence of a collision of stars or stellar debris similar to a demolition in the chaotic and dense region near the supermassive black hole of an ancient galaxy.
According to Andrew Levan, an astronomer at Radboud University in the Netherlands and lead author, “These new results show that stars can meet their end in some of the densest regions of the Universe, where they can be pushed into colliding. This is exciting. to understand how stars die and to answer other questions, such as what unexpected sources might create gravitational waves that we might detect on Earth,” he adds.
Ancient galaxies are long past their star formation stage and would have few, if any, giant stars left, which are the main source of long GRBs. However, their cores are packed with stars and ultra-dense stellar debris, such as white dwarfs, neutron stars, and black holes.
Astronomers have long suspected that in the turbulent hive of activity surrounding a supermassive black hole, it would only be a matter of time before two stellar objects collide to produce a GRB. However, evidence for this type of fusion has been elusive.
The first indications that such an event had occurred were observed on October 19, 2019, when NASA’s Neil Gehrels Swift Observatory detected a bright gamma-ray flash that lasted just over a minute. Any GRB that lasts longer than two seconds is considered “long”. Such outbursts typically 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 GRB’s glow to better understand its origins. The observations allowed astronomers to locate the GRB in a region less than 100 light-years from the nucleus of an ancient galaxy, placing it very close to the galaxy’s supermassive black hole. The researchers also found no indication of a corresponding supernova, which would leave its mark on the light studied by Gemini South.
“Our follow-up observation told us that rather than the collapse of a massive star, the outburst was most likely due to the merger of two compact objects,” Levan explains. “By determining its location at the center from a previously identified ancient galaxy, we obtained the first tantalizing evidence of a new pathway for stars to disappear.”
In normal galactic environments, the production of long GRBs from colliding stellar remnants such as neutron stars and black holes is thought to be extremely rare. However, the nuclei of ancient galaxies are anything but normal, and there may be a million or more stars crammed into a region only a few light-years across.
1687723745
#detect #powerful #gammaray #burst #neverbeforeseen #destroy #star #Daily #Listin
