- Andalusian scientists, in Nature: the gamma-ray burst requires revising the theory of starbursts.
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| Recreation of a gamma-ray burst. / Nuria Jordana-Mitjans / University of Bath |
The merger of two stars sheds light on the origin in the universe of gold or uranium
Scientists from the Instituto de Astrofísica de Andalucía (IAA-CSIC) have studied an explosion of gamma rays that, with a duration of almost one minute, suggests revising the theory of stellar bursts.
As reported by the IAA-CSIC in a statement, the study, published in the journal Nature this Wednesday, supports that the origin of the heavy elements in the universe, such as gold or uranium, would not be found in supernovae but in fusions of neutron stars.
Gamma-ray bursts (GRBs) are flashes associated with extremely energetic explosions that are detectable even in galaxies billions of light-years away, the Institute said. Its duration, considered short or long depending on whether it lasts more than two seconds, is associated with its origin: long outbursts occur with the death of very massive stars, and short ones with the merger of two compact objects, such as stars of neutrons, black holes, or both.
Gamma-ray bursts (GRBs) are flashes associated with extremely energetic explosions.
The study records the detection of a GRB lasting almost one minute produced by the collision of compact objects, which reconsiders the classification of these outbursts and opens up new scenarios in the death of stars.
As detailed by the CSIC, neutron stars are very compact and rapidly rotating objects that arise when a very massive star expels its envelope in a supernova explosion. The statement adds that it is known that the neutron star merger will produce a short burst of gamma rays, gravitational waves, and a kilonova, a phenomenon similar to supernovae, but whose energy comes in part from the decay of radioactive species and produces large amounts of elements heavy.
In fact, most of the gold and platinum on Earth are believed to have formed as a result of ancient kilonovae. "When studying the outburst, called GRB211211A, we observed clear indications that pointed to a kilonova, produced by the merger of two neutron stars, and not a supernova, the explosion with which very massive stars end their lives," says José Feliciano Agüí Fernández, a researcher at the Institute of Astrophysics of Andalusia who is participating in the study.
In fact, Agüí adds that the kilonova's luminosity, duration, and color are "similar to another well-known event that occurred in 2017, a neutron star merger that was the first observation of a cosmic event in light and in gravitational waves." The characteristic signature of kilonovae is their brightness in the near-infrared, much higher than their brightness in visible light. This difference is due to the fact that the heavy elements ejected by the kilonovae block visible light but not infrared, which presents a longer wavelength.
Coincident conclusions
"However, observing in the near-infrared is technically challenging and few ground-based telescopes can do it. This finding was made possible by the twin Gemini telescopes, which showed us that we were looking at a neutron star merger," says Jillian Rastinejad. , a researcher at Northwestern University (USA) who is leading the work. The conclusions of the scientific team, which also used data from other telescopes -among them the Hubble Space Telescope, the Gran Telescopio Canarias (La Palma), or the 2.2-meter telescope of the Calar Alto Observatory (Almería)-, coincide with those of another a group headed by the Tor Vergata University of Rome which, after studying the outburst with different approaches and observations, also concluded that it was produced by a kilonova.
In addition to contributing to the understanding of kilonovae and GRBs, this discovery provides a new way of studying the formation of heavy elements in the universe, the CSIC added.
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