by Researchers have synthesized five new isotopes that could help bring stars down to Earth – drawing scientists a step closer to understanding how collisions between ultra-dense, dead stars could produce heavy elements like gold and create money.
The isotopes are Thulium-182, thulium-183, ytterbium-186, ytterbium-187 and lutetium-190; this is the first time they have ever been synthesized on Earth. They were created by the Facility for Rare Isotope Beams (FRIB) at Michigan State University (MSU) and are a step towards building atoms on Earth that are normally only created in the ultra-turbulent environment surrounding the mergers of dead stars on their are called neutron stars.
“That’s the exciting part,” Alexandra Gade, FRIB’s scientific director and professor in USC’s Department of Physics and Astronomy, said in a statement. “We are confident that we can get closer to those nuclei that are important for astrophysics.”
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What is an isotope?
Each chemical element of the periodic table is defined by the number of protons in its atomic nucleus. For example, hydrogen has one proton, helium always has two protons, and iron has 26. Hydrogen cannot have two protons, and iron cannot have 25; if they did, they would no longer contain hydrogen or iron.
However, neutrons bind to protons in atomic nuclei, and the number of these particles can change without changing the nature of an element. Nuclei with different numbers of neutrons are called isotopes of an element. Thus, iron isotopes include iron-54 with 26 protons and 28 neutrons, iron-56 with 26 protons and 30 neutrons, and iron-57 with 26 protons and 31 neutrons.
The five newly synthesized isotopes are exciting, however, because they are not commonly found on our planet. In fact, they weren’t even received on our planet before.
“This is probably the first time these isotopes have been on Earth’s surface,” Bradley Sherrill, University Distinguished Professor in USC’s College of Natural Sciences and head of the Advanced Rare Isotope Separator Department at FRIB, said in the statement. “I like to draw the analogy of making a journey. We look forward to going somewhere we’ve never been before, and this is the first step. We’ve left home, and we’re starting to explore.”
Superheavy isotopes and superheavy elements
Stars in general can be thought of as nuclear furnaces that forge the elements of the universe, starting with the fusion of hydrogen into helium, which is then fused to create nitrogen, oxygen and carbon.
The largest stars in our Universe can forge elements in the periodic table all the way up to iron, but scientists believe that even these powerful furnaces are not enough to create elements heavier than that. But, what happens if two stars enter their furnaces? And rather violent at that?
The thing is, when they die, massive stars are left with iron cores that can no longer fuse into heavier elements, the energy that supported these stars against the push of their gravitational pull is also gone. own. This causes the cores to collapse as the outer layers are dispersed by powerful supernova explosions.
However, this collapse can be stopped when the electrons and protons in these cores are transformed into a sea of neutrons, which a feature of quantum physics known as “degeneracy” prevents them from cramming together. This degeneracy pressure can be overcome if the stellar core has enough mass, causing it to completely collapse and form a black hole. But sometimes there is not enough mass. These remain as dead, super-intense neutron stars.
Furthermore, this process does not stop nuclear fusion for neutron stars if they happen to exist in a binary system with another massive star that also eventually collapsed to give birth to a neutron star. As these ultradense stars with masses one to two times that of the sun enter orbits about 12 miles (20 kilometers) around each other, they release ripples in spacetime known as gravitational waves.
Those gravitational waves carry angular momentum away from the system, causing the neutron stars to pull together and emit more gravitational waves at greater intensities. This continues until the two eventually meet.
Not surprisingly, due to their extreme nature, collisions of binary neutron stars create a very violent environment. The event scatters neutron-rich material, for example, which is believed to be important for the synthesis of gold and other heavy elements.
That is because these free neutrons can capture other atomic nuclei in the environment called the fast capture process or “e-process.” These greedy atomic nuclei then grow heavier, creating a heavy isotope that is unstable. These unstable isotopes are expected to eventually decay into stable elements, such as gold, which are lighter than heavier elements but still heavier than iron.
“It’s not certain, but people think that all the gold on Earth was made in neutron star collisions,” Sherrill said. In fact, the James Webb Space Telescope found the best evidence yet for the theory.
So how do we know if this process happens with certainty?
If scientists could recreate the superheavy elements involved in the e-process, they could gain a better understanding of the creation of gold and other heavy elements. Alas, the creation of Thulium-182, thulium-183, ytterbium-186, ytterbium-187 and lutetium-190. These isotopes, formed by firing a platinum ion beam at a carbon target at FRIB, may not be present in the destruction of neutron star collisions, but they are certainly a step towards those transitional heavy elements that inhabit to briefly create the Earth. see planets if they are the result of elements like gold.
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In this way, a better understanding of these newly created isotopes could have important implications for nuclear physics.
“It’s not a big surprise that these isotopes exist, but now that we have them, we have colleagues who will be very interested in the next step we can measure,” Gade said. “I’m already thinking about what we can do next in terms of measuring their half-lives, masses, and other properties.”
The team’s research was published Thursday (February 15) in the journal Physical Review Letters.
