Astronomers have stumbled upon an unprecedented phenomenon that presents a novel method for obliterating a star.
Astronomers have recently uncovered a novel star-destroying phenomenon that reveals more incredible details about our universe. In their quest to uncover the roots of a potent gamma-ray burst (GRB), an international squad of astrophysicists may have unveiled a previously unknown method to obliterate a star.
So, what are Gamma-ray Bursts? Gamma-ray bursts, which are believed to occur during the creation of black holes, are the most potent and luminous eruptions known in the cosmos. Despite their brief duration of mere seconds, these bursts unleash a staggering amount of energy equivalent to what the sun would emit over its entire lifespan of 10 billion years.
Contrary to most GRBs, which stem from massive explosive stars or neutron-star mergers, GRB 191019A is believed to be born from star or stellar remnant collisions in the crowded surroundings of a supermassive black hole at the core of an ancient galaxy. This chaotic environment suggests an unseen yet theorized path to star destruction and GRB production.
Novel Star-Destroying Phenomenon
The research, published June 22 in Nature Astronomy, was directed by Radboud University in the Netherlands, with contributions from Northwestern University astronomers. Northwestern astrophysicist Wen-fai Fong, a co-author of the study, noted, “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.” These unusual cases provide insights into the universe’s stunning array of explosions.
The discovery of these extraordinary events in dense stellar systems, particularly those enveloping supermassive black holes at galaxy cores, is thrilling, said Northwestern astrophysicist and co-author Giacomo Fragione. These environments serve as factories for otherwise impossible occurrences, offering a glimpse into their complex dynamics.
Traditional Star Deaths and a New Player
Stars typically meet their end in one of three predictable ways, depending on their mass. Like our sun, low-mass stars shed their outer layers, fading into white dwarf stars. More massive stars, however, burn brighter, and explode faster in devastating supernovae, creating ultra-dense bodies like neutron stars and black holes. The third scenario involves the collision of two such remnants. This study, however, suggests a fourth possible fate for stars.
A Novel Star-Destroying Phenomenon at the Heart of Ancient Galaxies
“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,” stated lead author Andrew Levan of Radboud University. These findings broaden our understanding of star deaths and could reveal unexpected sources of gravitational waves detectable on Earth.
Ancient galaxies, having exhausted their star-forming capabilities, harbor few, if any, remaining massive stars. Their cores, however, are swarming with stars and a zoo of ultra-dense stellar remnants. Astronomers have suspected that the turbulent surroundings of a supermassive black hole would eventually trigger a GRB-causing collision. However, evidence for such a merger remained elusive until now.
Merging Stellar Remnants and GRB
On Oct. 19, 2019, NASA’s Neil Gehrels Swift Observatory detected a bright flash of gamma rays, lasting just over a minute. Any GRB longer than two seconds is considered “long”, typically resulting from the collapse of stars with at least 10 times the mass of our sun.
The research team used the Gemini South telescope in Chile to monitor the GRB’s fading afterglow, pinpointing the GRB location to a region less than 100 light-years from the nucleus of an ancient galaxy, very near the galaxy’s supermassive black hole.
Unlocking Cosmic Secrets
A lack of a corresponding supernova hints at the unconventional nature of this GRB. The location of GRB 191019A suggests a new theory for the formation of gravitational-wave emitting sources.
Long GRBs from colliding stellar remnants are extremely rare in typical galactic environments. However, in the packed cores of ancient galaxies, the high population density might lead to occasional stellar collisions under the influence of a supermassive black hole. This could set off a tremendous explosion, observable from great cosmic distances.
The First of Many?
These events could occur regularly in similarly crowded regions across the universe but may have remained undetected due to obscuring dust and gas. The discovery of GRB 191019A opens the door to detecting more of these elusive events.
“While this event is the first of its kind to be discovered, it’s possible there are more out there that are hidden by the large amounts of dust close to their galaxies,” Fong said. By discovering more of these events, the researchers hope to link a GRB detection with a corresponding gravitational-wave detection, further revealing their nature and origins.
Have something to add? Visit Curiosmos on Facebook. Join the discussion in our mobile Telegram group.
