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Astronomers have observed a supernova like never before, and it could be an important evidence of a significant type of star death that would have shaped the early galaxies.
The supernova, called SN2016iet, does not fit into the classification systems used by scientists for supernovae. It looks like a "pair-instability supernova" that would occur among the heaviest stars.
And according to the research team, led by Sebastian Gomez, a graduate student at Harvard University, he could act as the most massive star ever seen at a supernova.
"Finding something as different from everything we know is exciting," said Edo Berger, author of the study and professor of astronomy at Harvard University. Gizmodo.
The Gaia Telescope for Milky Way Mapping was first sighted on November 14, 2016. It was later found by topographic telescopes, including the Catalina Real-Time Transient Survey and the Transient Passenger Survey. from the company Pan-STARRS. Astronomers continue to observe the resulting blip, including its brightness and the identity of the elements it contains.
How is this supernova different? On the one hand, most supernovae flash once and then disappear from the view of astronomers after a few months. But the SN2016iet is brightened and dimmed twice, and its remains persist to this day.
Its spectral signature contains no trace of hydrogen or helium, which would normally place it in one of the other categories of supernovae, but SN2016i and shows non-equivalent calcium and oxygen abundances in the other supernova observations.
Even the place where it occurred was strange, far from the center of a galaxy with an unusually low level of heavier elements.
Three years of observations and mathematical modeling show that the star could have been once 130 to 260 times the mass of the Sun. Over time, it would have lost most of its external hydrogen and helium, becoming a dense core of heavier elements left behind by the melting.
If the models are correct, then the gamma rays that would normally create an external pressure in the nucleus would be absorbed by the neutrons of these heavier elements, and the star would collapse of its own accord. the weight of his own gravity. The result would be a nuclear explosion, a process called supernova with pair instability.
It is the first candidate of this type with pair instability in which the quantity of heavier elements and the mass deduced from the initial star are part of the theoretical predictions, according to the article published in The astrophysical journal.
It is an exciting object, but there is certainly more to study. "The parameters they need for this scenario, including ejecting material very early before the explosion, are not well explained by current models in this class," said Kate Maguire, assistant professor at Trinity College Dublin. Gizmodo in an email.
"The main limitation of the article is that the theoretical models developed so far can not explain all the properties, so it is impossible to clearly determine the type of star that exploded and how."
If this supernova was really a pair-instability supernova, it's exciting, Berger said. "I think these explosions were probably more common in the early universe," among the first generation of massive stars. These supernovae could have shaped the current appearance of the chemical composition of galaxies. SN2016iet could be a local example of something otherwise limited to the most distant universe.
Physicists will use the Hubble Space Telescope to continue exploring this strange object in 2021.
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