Astronomers observe a new type of supernova named SN 2016iet. It gives us a new perspective about the way giant stars ended in the early universe.
SN 2016iet happened in a dwarf galaxy about 900 million light-years away from us. It might be the strongest explosion ever observed to date.
This new type of supernova can completely annihilate its parent star, therefore leaving no remnant behind.
“When we first realized how thoroughly unusual SN2016iet is, my reaction was ‘whoa – did something go horribly wrong with our data?'” said Mr. Sebastian Gomez, Harvard University graduate student and lead author of the paper. “After a while, we determined that SN2016iet is an incredible mystery, located in a previously uncatalogued galaxy one billion light-years from Earth.”
Astronomers first spotted it with the ESA’s star-mapping Gaia satellite on November 14, 2016.
After nearly three years of observations, a team of astronomers concluded that the SN 2016iet supernova began as a star 200 times the mass of the Sun. The star had formed in an isolated zone about 54,000 light-years from the center of its host dwarf galaxy.
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The star lost 85% of its mass during a short life of only a few million years before it exploded. The material shed before its death collided with the debris from the explosion. This led to SN2016iet’s unusual appearance, providing scientists with the first strong case of a pair-instability supernova.
A pair-instability supernova occurs when the core of a dying star produces gamma-rays. Therefore leading to the formation of particle and antiparticle pairs, which causes a thermonuclear blast that destroys the star.
“The idea of pair-instability supernovas has been around for decades,” Berger said. “But finally having the first observational example that puts a dying star in the right regime of mass, with the right behavior, and in a metal-poor dwarf galaxy is an incredible step forward.”
“Everything about this supernova looks different, its change in brightness with time, its spectrum, the galaxy it is located in, and even where it’s located within its galaxy,” Edo Berger, an astronomy professor at Harvard University and co-author of the study, said in the statement. “We sometimes see supernovas that are unusual in one respect but otherwise are normal; this one is unique in every possible way.”
SN 2016iet supernova also had an incredibly long duration and large energy, unusual chemical fingerprints, and lack of metals in its environment – none of which has been observed in other supernovae.