Far out cosmology: stars making heavy elements (Introduction)

by David Turell , Thursday, December 07, 2023, 20:16 (350 days ago) @ David Turell

A study finds a limit of 260 atomic weight:

https://phys.org/news/2023-12-ancient-stars-extraordinarily-heavy-elements.html

"How heavy can an element be? An international team of researchers has found that ancient stars were capable of producing elements with atomic masses greater than 260, heavier than any element on the periodic table found naturally on Earth. The finding deepens our understanding of element formation in stars.

"We are, literally, made of star stuff. Stars are element factories, where elements constantly fuse or break apart to create other lighter or heavier elements. When we refer to light or heavy elements, we're talking about their atomic mass. Broadly speaking, atomic mass is based on the number of protons and neutrons in the nucleus of one atom of that element. (my bold)

"The heaviest elements are only known to be created in neutron stars via the rapid neutron capture process, or r-process. Picture a single atomic nucleus floating in a soup of neutrons. Suddenly, a bunch of those neutrons get stuck to the nucleus in a very short time period—usually in less than one second—then undergo some internal neutron-to-proton changes, and voila! A heavy element, such as gold, platinum or uranium, forms.

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"'We have a general idea of how the r-process works, but the conditions of the process are quite extreme," Roederer says. "We don't have a good sense of how many different kinds of sites in the universe can generate the r-process, we don't know how the r-process ends, and we can't answer questions like, how many neutrons can you add? Or, how heavy can an element be? So we decided to look at elements that could be made by fission in some well-studied old stars to see if we could start to answer some of these questions."

"The team took a fresh look at the amounts of heavy elements in 42 well-studied stars in the Milky Way. The stars were known to have heavy elements formed by the r-process in earlier generations of stars. By taking a broader view of the amounts of each heavy element found in these stars collectively, rather than individually as is more common, they identified previously unrecognized patterns.

"Those patterns signaled that some elements listed near the middle of the periodic table—such as silver and rhodium—were likely the remnants of heavy element fission. The team was able to determine that the r-process can produce atoms with an atomic mass of at least 260 before they fission.

"'That 260 is interesting because we haven't previously detected anything that heavy in space or naturally on Earth, even in nuclear weapon tests," Roederer says. "But seeing them in space gives us guidance for how to think about models and fission—and could give us insight into how the rich diversity of elements came to be.'"

Comment: we are the results of exploding stars. dhw thinks the universe is too big as designed by God. We need all those exploding stars to be created here.