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Scientists just got to watch nearly the entirety of a kilonova explosion caused by a neutron star merger, thanks to a multi-national telescopic effort.
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The kilonova briefly mimicked the conditions immediately following the Big Bang, and allowed scientists to confirm the source of the heavy elements Strontium and Yttrium for the very first time.
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The massive explosion also produced the smallest black hole ever observed.
When stars die, they don’t do it all at once. It’s a slow, arduous process during which they cycle through less and less efficient energy sources while trying to stay alive. They switch from hydrogen to helium to carbon and on and on, until they hit iron. But iron is a terrible fuel. Eventually, it’s just not enough, and…
Boom.
In addition to producing colossal and awe-inspiring supernovae, these death cycles are also the universe’s predominant sources of the elements they use to fight off their ultimate fate. Helium, oxygen, neon, iron—they all come from the fusion that takes place in dying stars.
But we have a lot of elements that are more massive than iron; it’s only element 26 of 118, after all. So, where do all of the other elements come from?
We’re pretty sure they’re formed in the actual moments of explosion throughout the universe—super-hot supernovae, stellar mergers, and similar events that produce enough energy to power this kind of high-level fusion. But those things are remarkably hard to spot when you have a whole universe to search through, and so we’ve never actually seen the heavier elements being produced.
Until now. In a recent study that appears in Astronomy and Astrophysics, scientists describe watching these elements be produced for the very first time in a massive explosion known as a kilonova.
The scientists got to see this kilonova pretty much in its entirety, thanks to multiple teams working together across multiple telescopes to capture the event. “This astrophysical explosion develops dramatically hour by hour, so no single telescope can follow its entire story,” lead study author Albert Sneppen said in a press release.
“The viewing angle of the individual telescopes to the event are blocked by the rotation of the Earth. But by combining the existing measurements from Australia, South Africa, and The Hubble Space Telescope we can follow its development in great detail. We show that the whole shows more than the sum of the individual sets of data.”
Kilonovae occur when two neutron stars (the collapsed cores of truly gigantic dead supergiant stars) smash into each other. The resulting explosion is wildly hot—so hot that the immediate area actually briefly resembles the conditions extant in the universe one single second after the Big Bang, resulting in a soup of rogue electrons and unconnected atomic nuclei known as ionized plasma.
According to the press release, when the universe was first born and full of ionized plasma, it took a full 370,000 years for conditions to cool enough for atoms to form and for light to start making its way through the cosmos. We call that first emerging light cosmic microwave background radiation, and it’s the oldest information we have on the universe.
But luckily, scientists didn’t have to wait that long for their kilonova to give up its information. Fairly quickly, the scientists were able to detect the existence of Strontium and Yttrium, confirming exactly where those elements come from for the very first time. It also resulted in the smallest black hole ever observed.
“We can now see the moment where atomic nuclei and electrons are uniting in the afterglow,” Rasmus Damgaard, co-author of the study said in the press release.
“For the first time we see the creation of atoms, we can measure the temperature of the matter and see the micro physics in this remote explosion. It is like admiring the cosmic background radiation surrounding us from all sides, but here, we get to see everything from the outside. We see before, during, and after the moment of birth of the atoms.”
Over and over again, the universe proves itself willing to share its secrets with us if we look close enough. And as long as we keep looking, it certainly seems like there will always be more to see.
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