Astronomers have observed a supernova that has never been seen before, and it could be a strong indication of a major type of star death that would have shaped early galaxies.
The SN2016iet supernova does not fit with the classification schemes that scientists use today for supernovae. It looks like a "paired instability supernova" that would occur under the heaviest stars.
And, according to the research team led by Sebastian Gomez, a Harvard University graduate student, this may be the most massive star ever seen in a supernova Berger, study author and astronomy professor at Harvard University, reported Gizmodo .
The Gaia Telescope mapping the Milky Way discovered the lightning on November 1
How is this supernova different? For one, most supernovas flash once and then disappear after a few months from the perspective of astronomers. But SN2016iet became twice lighter and darker, and its remains persist to this day.
Its spectral signature contains no evidence of hydrogen or helium, which would normally place it in one of the other supernova categories, but SN2016iet shows a frequency of calcium and oxygen that does not match in other supernova observations.
Even the place where he appeared was strange, far from the center of a galaxy with unusually little heavier elements.
Three years of observations, along with mathematical models, show that the star could once have been 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 over from fusion.
If the models are correct, the gamma rays that would normally create a pressure outward in the nucleus will instead be absorbed by the neutrons of those heavier elements, and the star would collapse under the weight of its own gravity. The result would be a nuclear explosion, a process called pair-instability supernova.
This is the first such pair instability candidate in which the number of heavier elements and the deduced mass of the starting star correspond to the theoretical predictions of the article published in The Astrophysical Journal .
It's an exciting object, but there's definitely more to study. "The parameters they need for this scenario, especially the ejection of material just before the explosion, are not well explained by current models in this class," said Kate Maguire, assistant professor at Trinity College, Dublin, opposite Gizmodo in an e-mail.
"The main limitation of the work is that the theoretical models that have been created so far can not explain all their properties, and therefore there is no definite conclusion as to which star type exploded like."
If so Supernova was really a pair-instability supernova, that's exciting, Berger said. "I think these explosions were probably more common in the early universe," under 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 that is otherwise confined to the farthest universe.
Physicists will use the Hubble Space Telescope to explore this strange object until 2021.