Stars are great. Our own star, the Sun, is one of the big reasons why we’re all here today. Without it, we’d be goners, but while stars can be life-giving, they can also be incredibly destructive forces of nature. As recent observations by NASA and astronomers around the world have shown, the death of a star can produce a truly cataclysmic release of energy that would destroy just about everything in its path.
On August 29th, 2019, scientists around all over the Earth were alerted to an intense event taking place roughly one billion light-years away. It was a massive gamma-ray burst, and while a billion light-years is an almost unfathomable distance, this event was unique among gamma-ray bursts. The huge distance is actually much closer to our planet than gamma-ray bursts scientists have observed in the past, and it offered them an opportunity to study the event in a new way.
As researchers explain in a new paper published in the journal Science, the typical distance of a gamma-ray burst from Earth is around 20 billion light-years. This latest event, labeled GRB 190829A, was so close that scientists considered it a “front-row view” of the death of the star and the burst of energy it produced as it died.
“Gamma-ray bursts are bright X-ray and gamma-ray flashes observed in the sky, emitted by distant extragalactic sources,” Sylvia Zhu, co-author of the work, said in a statement. “They are the biggest explosions in the universe and associated with the collapse of a rapidly rotating massive star to a black hole. A fraction of the liberated gravitational energy feeds the production of an ultrarelativistic blast wave. Their emission is divided into two distinct phases: an initial chaotic prompt phase lasting tens of seconds, followed by a long-lasting, smoothly fading afterglow phase.”
It’s this afterglow phase that scientists had the best opportunity to observe, as the actual burst happens so fast that it is difficult to observe in great detail. The researchers gathered data from observatories around the planet which were able to observe the energy as it pierced space.
“We could determine GRB 190829A’s spectrum up to an energy of 3.3 tera-electronvolts, that’s about a trillion times as energetic as the photons of visible light,” Edna Ruiz-Velasco, co-author, explains. “This is what’s so exceptional about this gamma-ray burst – it happened in our cosmic backyard where the very-high-energy photons were not absorbed in collisions with background light on their way to Earth, as it happens over larger distances in the cosmos.”
Ultimately, while this gamma-ray burst was much closer than they typically are, scientists would benefit from being able to observe one happen right before their eyes. Detecting these events and then rushing to point telescopes in the right direction produces some great data, but more could be learned if scientists could predict when a star is going to die and see the action as it happens.
